If we look in the dictionary, the definition is far too restrictive:
Apnea n.f. (from Greek pnein, breathe). Suspension, voluntary or not, of breathing. Snorkel
Apneist n. Person who enjoys diving underwater.
One could find a multitude of other definitions, each apneist having his own definition of apnea: search for well-being; way to evacuate stress; means to control one’s body, breathing and heart rate; learn to listen to your body want to go beyond; search for depth; desire for extreme sensations; purpose of competition; the big Blue; Pranayama; ….
Apnea, just like scuba diving, also allows you to discover the water, the sea and its inhabitants. But, we have a lot more freedom in freediving than scuba diving: no need to wear bulky and heavy equipment; we can stay in the water for 4 hours if we feel like it, while in dive we are limited by the amount of air in the bottle. It is often (not always!) scuba divers who sign up for training with AIDA, as part of their own club training they practice regularly.