Freediving is as ancient an activity as humanity itself. More than any other sport, freediving is based on old subconscious reflexes written in the Homo Sapiens genome.
For the first 9 months of their lives, humans exist in an aquatic environment very similar to seawater. If a human infant is submerged under water, it instinctively holds its breath for up to 40 seconds while making swimming motions, although we seem to lose this ability as soon as we commence walking. Waking up these reflexes is one of the most important elements of freediving, thus giving humans better abilities to be protected at large depths.
The word Apnea derives from the Greek word a-pnoia literally meaning "without breathing". The origin of this word doesn't have connection to water, but in modern athletic terminology "Apnea" has become a synonym for freediving, i.e. diving on one breath of air, without using equipment that would make it possible to breathe underwater.