Term	Definitions
A.I.D.A.	Association Internationale pour le Développement de l'Apnée – one of the main international freediving agencies
aerobic	Cellular metabolism with oxygen, requiring oxygen for breathing
air embolism	Obstruction of the circulatory system caused by an air bubble as e.g. as a complication from scuba diving [syn: aeroembolism] 2: pain resulting from rapid change in pressure [syn: decompression sickness, aeroembolism, caisson disease, bends]
anaerobic	Not aerobic – not needing or without oxygen – an activity in which the body incurs an oxygen debt
anaerobic metabolism	Creation of energy through the combustion of carbohydrates in the absence of oxygen. This occurs when the lungs cannot put enough oxygen into the bloodstream to keep up with the demands from the muscles energy. Generally used for short busts of activity
apnea	From the Greek, it means "without, or not breathing".
ascent bo	Blacking out while ascending from a dive, if it happens, it's usually in the last 10 – 15 meters
ascent rates	Speed at which one ascends from a dive
barotraumas	An injury that results due to rapid or extreme changes in pressure.
bi-fins	Traditional swimming fins – one for each foot
blackout	Losing consciousness during breath-hold activities
blood PH	Level of acidity/alkalinity in the blood
blood shift	Related to the mammalian diving reflex - to prevent collapse under great pressure, the wall of the lungs fill with blood from other parts of the body.
bo	See: Blackout
bottom time	Time spent underwater during a dive while freediving, or the time spent lingering at the bottomweight/plate
bradycardia	Part of the mammalian diving reflex: Slowing down of the heart rate and pulse
breathing oxygen	Breathing pure oxygen as a therapeutic measure or as a preparation for increasing one's time underwater.
breath-up	Set of breathing procedures done before a long immersion – used to build up the capacity of the body in order to spend more time underwater on a single breath.
carp breathing	See: Packing
certifying agencies	Official freediving agencies that have the authority to certify the different local, national and world freediving records.
clogged ear	Having the ear canal of the outer ear obstructed, also called swimmers ear.
CMAS	CMAS is an international organisation to promote SCUBA diving and other underwater sports. Founded by J.Y. Cousteau
CO2 narcosis	Toxicity resulting from too high levels of carbon dioxide in the blood
CO2 tolerance	Tolerance to carbon dioxide in the blood
collapsed lung	A collapsed lung, or pneumothorax, involves the collapse of the tissues of part or all of one lung so that oxygen cannot be absorbed into the blood stream in the normal way. Changes in pressure during diving may cause tissue damage. See also: pneumothorax
constant ballast	See: Constant weight
constant weight	One of the freediving disciplines: Diving down as deep as one can and ascending without the use of any mechanical device and rope. The weight of the freediver must remain the same during descent and ascent.
contractions	After a certain time without sufficient oxygen, the diaphragm starts to flutter and also experience contractions in order to "remind" the body that it needs to breath.
countdown time	The time just prior to a dive or static apnea. It is usually called out in a competition to help freedivers time their preparation and breath-up prior to the dive.
cramps	A sudden and involuntary tightening of a muscle – usually can be quite painful. Cramps usually happen in the legs for swimmers and freedivers.
Crazy Cuban	Diving as deep as possible with no aids whatsoever – no mask, fins, or weight belt. Also favoured by the freediver Sebastian Murat.
DCI	See: decompression sickness. Acronym for Decompression Illness
DCS	See: decompression sickness
decompression	Procedure used by scuba divers to reabsorb the nitrogen that has built up in the blood stream during long and deep dives
decompression chamber	A pressurized chamber used to reproduce the pressures found at great depths. Usually used to help divers recover from decompression sickness.
decompression sickness	Physiological disorder caused by a rapid decrease in atmospheric pressure, resulting in the release of nitrogen bubbles into the body tissues. It is also known as caisson disease, altitude sickness, and the bends
DEMA Dive Show	Diving Equipment & Marketing Association – Trade fair organization
depth adaptation	The capacity of the lungs to adapt to the pressure found at great depths. fotos si Precio?
dive computers	Computer that can measure the depth and time spent at each depth. It also calculates the recommended decompression times needed by the diver.
diving response	Lowering of the heart rate and constriction of the blood vessels in the body causing blood to be redirected to the brain and heart to keep the important vital functions active.
dizziness	Disorientation of the sense of balance – vertigo.
dry static	Static apnea on dry land.
dynamic apnea (with fins)	One of the disciplines of freediving: swimming underwater as far as one can with fins.
dynamic apnea (without fins)	One of the disciplines of freediving: swimming underwater as far as one can without any type of fins.
ear jamming	When the Eustachian Tubes close and no amount of pressure seems to open them during a dive
embolism	See: Air embolism
empty lung dives	Refers to "negative pressure dives" where freedivers prepare their lungs for very deep dives by emptying them of air and diving several meters. The lack of air pressure in the lungs simulates diving to a much greater depth and is useful as a warm up excercise
equalization	Balancing the air pressure in the middle and outer ear.
equalize	The act of equalizing the pressure difference between the middle and outer ear. There are several techniques. The two main ones are the Valsalva and the Frenzel techniques.
Eustachian tube	A tube that connects the middle ear with the nasopharynx and permits the equalization of pressure on both sides of the eardrum. It is bony and cartilaginous.
F.R.E.E.	Freediving Regulations & Education Entity – Freediving teaching agency, less active
failure depth, breakpoint	The depth where lung pressure turns negative and below that it is difficult -or impossible- to bring air in the mouth for equalization
fire breathing	Slow shallow breathing, slowed by half closing epiglottis. The idea is to keep a nearly continuous 'greater-than-ambient' pressure in the lungs.
fluid goggles	Diving mask containing liquid instead if air to avoid using up valuable air equalizing the mask at depth. May have corrective lenses to adjust for the liquid the eyes have to see through.
free ascent dangers	The dangers of ascent, could be decompression sickness (rare in freedivers), shallow water blackout (most common danger), and overstretching of the lungs after having packed allot. (Also very rare)
free immersion	One of the disciplines of freediving: diving as deeply as one can without fins and pulling one's self down and up a guide rope.
freediving	The fine art of diving without using any breathing apparatus. Freediving can be competitive or recreational.
Frenzel Technique	Equalization technique involving using the tongue as a piston to force air through the Eustachian Tubes.
haemoglobin	Protein in the red blood cells which combines with and carries oxygen around the body, and gives blood its red colour
heavy packing	Packing allot of air into the lungs – some freedivers can pack up to 4 liters of extra air into their lungs.
HMS Dolphin	A special 30 meter deep swimming pool in the UK designed for training submariners to escape from a submarine at 30 meters on a single breath. Freedivers can also use the HMS Dolphin paying a fee.
hook breathing	Taking a deep breath after a long breath–hold and bearing down on it for a couple of seconds to speed up the transfer of oxygen from the lungs to the rest of the body as well as to force blood up to the head and keep the O2 moving.
hyperbaric chamber	A pressurised chamber that allows for the delivery of oxygen in higher concentrations for therapeutic benefit – useful for decompression illness
hyperbaric oxygen therapy	The therapeutic intermittent administration of oxygen in a chamber at greater than sea-level atmospheric pressures (three atmospheres). It is considered effective treatment for air and gas embolisms as well as for decompression illness.
hypercapnia	Too much carbon dioxide in the blood
hyperoxia	Too much oxygen in the blood
hyperventilation	Hyperventilation is the practice of excessive breathing with an increase in the rate of respiration or an increase in the depth of respiration, or both
hypocapnia	Lower than normal carbon dioxide in the blood stream, can result from hyperventilation and bring on blackout sooner than normal.
hypothermia	When a person's body temperature falls below normal due to exposure to extreme cold. This is a dangerous condition that can result in death.
hypothermic diving system	System devised by Eric Fattah taking advantage of steep thermoclines to induce hypothermia therefore increasing the diving reflex to be able to dive deeper.
hypoxemia	Lower than normal oxygen in arterial blood which gives rise to hypoxia.
hypoxia	Lower than normal oxygen supply to tissues even though there might be a proper amount of blood in the tissues.
IAFD	International Association of Free Divers – Freediving teaching Agency, less active
lactic acid	Lactic acid is a by-product of anaerobic glycolysis and anaerobic metabolism. Although used as a fuel by the heart, excessive lactic acid slows down contractions of the skeletal muscles, preventing you from walking fast
LMC	Loss of Motor Control – also known as "samba". It occurs when the muscles have almost no oxygen and suffer seizures. It happens just before blackout.
lung fluid	Fluid i.e. plasma filling the walls (alveolis) of your lungs is a response to the increased pressure at depth (usually at around 50m but it can vary quite a bit depending how much air you have in your lungs and your residual volume) to protect your lungs and other organs.
Lung packing	See: Packing
lung squeeze	See: pulmonary edema.
lung training	Training the lung to have more strength and capacity
lung volume	Amount of air in the lungs, also known as TLC
mammalian diving reflex	See: diving response
mask air	The amount of air in the mask. There are high–volume and low–volume masks. Freedivers prefer low–volume air as they are easier to equalize.
mask pumping	Technique for utilizing the air in one's mask during ascent. See: rebreathing
mask volume	See: Mask air
Middle-Ear Barotrauma	Middle–Ear problems due to quick changes in pressure. It can happen on ascent when the pressure in the outer ear diminishes faster than in the inner ear. Also known as "reverse squeeze".
monofins	Fins based on the design of a dolphin's tail. Both feet fit into a single monofin. Even though hard to use at first, they provide greater power and speed than bi–fins.
N2 narcosis	See: nitrogen narcosis
narcosis	See: nitrogen narcosis
negative pressure dives	See: Empty lung dives
newbie	Someone new to a particular activity, a beginner
nitrogen narcosis	Mental state similar to euphoria, drunkenness and disorientation caused by the narcotic effects of the air's nitrogen at high pressure. Divers often exhibit dangerous behaviour such as ditching equipment underwater. Also known as rapture of the deep.
no limits	One of the disciplines of freediving: Descending as far as possible with ballast equipment (usually a sled) and ascending with an air balloon or similar.
nose clip	Device that closes the nostrils to prevent water getting in or air getting out.
O2 levels	Levels of oxygen in the blood
oxygen narcosis	See: oxygen toxicity
oxygen toxicity	Occurs when one breathes high partial levels of oxygen in the blood stream. Symptoms can be deep fatigue while breathing, muscular twitching, anxiety, confusion, incoordination, and convulsions including visual and auditive abnormalities
pack stretching	Stretching of the lungs due to packing
packing	Special techniques for filling the lungs with more air than normally possible.
PaCO2	Partial pressure of arterial carbon dioxide in the blood
PB	Acronym for "Personal Best"
peripheral vasoconstriction	It has been shown that at depth, blood flow is shunted from the limbs to those organs whose oxygen consumption is critical, the heart and brain
personal bests	One's best record in any of the disciplines of freediving
pipe mask	Diving mask with a small tube extending from the mask to mouth for equalizing.
pneumothorax	A condition in which air or other gas is present in the pleural cavity and which occurs spontaneously as a result of disease or injury of lung tissue or puncture of the chest wall or is induced as a therapeutic measure to collapse the lung. See also: Collapsed lung
Powerlung	Training instrument used for enhancing lung capacity.
pranayama	Yogic breathing techniques for balancing and enhancing the body's vital energies.
pulmonary edema	Dangerous medical condition where the lung fills with increased interstitial fluid causing the alveoli to flood with the fluid and be coated in blood, thus reducing the alveoli's capacity to transfer oxygen.
rebreathing	In relation to freediving: Sniffing or rebreathing the expanding air in one's mask while ascending. Also known as "mask pumping"
recreational freediving	Freediving for pure and simple fun!
residual lung volume (RV)	The volume of air that remains in the lungs after exhaling completely
Reverse Squeeze	See: Middle–Ear Barotrama
RV	See: Residual lung volume
S.A.F.E.R.	"Specialized Advanced Freediving Enhancement & Reliability " – Freediving teaching agency, less active
samba	Loss of muscle control commonly known as “samba”, preceding blackout in many cases.
SaO2	Saturation of Oxygen (arterial blood)
security rope	Guide rope or line used to orient the freediver while descending, also known as the rope or the diverope.
shallow water blackout	Sudden loss of consciousness caused by pressure drop in oxygen.
skindiving	Swimming underwater or on the surface usually with the help of a face mask, fins, and a snorkel
solo freediving	Freediving alone without a buddy
spirometer	Medical instrument used to measure vital lung capacity
spotting	Having a buddy watch you for safety reasons while engaging in freediving activities either in the swimming pool or the sea.
static apnea	One of the disciplines of freediving: Seeing how long one can hold one's breath while floating on the surface with the face submerged.
suit squeeze	"Suit squeeze", where the hood of a stretchy wetsuit 'seals' around the outer ear, trapping air in the outer ear. This can cause problems due to incorrect equalizing on descent or ascent.
surface intervals	Time spent at the surface between dives
SWB	See: Shallow water blackout
tear duct equalization	Equalization (of the mask?) through the tear ducts
tidal volume	The volume of air normally inhaled or exhaled when one is making no extra effort.
TLC	See:Total Lung Capacity
total lung capacity (TLC)	Total Lung Volume: The sum of RV and VC
variable ballast	One of the freediving disciplines: Going down with a weighted device and coming up pulling on a rope or swimming
vasoconstriction	See: peripheral vasoconstriction
VC	See: Vital Capacity
ventilation	More than normal breathing, less than hyperventilation.
vital capacity (VC)	The amount of air of a complete and full exhalation including the expiratory reserve volume
warm ups	Preparative exercises previous to an activity requiring great physical effort. Usually different kind of dives.
weight belt ditching	Releasing the weight belt
weighting	Applying the correct amount of weight for one's freediving or scuba needs
weights	Usually lead weights used for counteracting the body's (and wetsuit's) natural buoyancy.
wet lung	Also known as Pulmonary Edema: The abnormal accumulation of liquids in the lungs due to rapid changes in pressure. Different from lung fluid, this is harmful and can lead to secondary drowning.
wet statics	Static apnea in the pool or sea

Adrian Valls (edited by Sebastian Näslund)