(parachuting) Acronym of high altitude, low opening. A type of skydiving where one leaves the launch platform from a high altitude and opens the parachute at a very low altitude.

(advertising slang) To add vitamins to a food product as a dietary supplement.

of or relating to polyphony / (music) having two or more independent but harmonic melodies; contrapuntal / (of an electronic device) able to play more than one musical note at the same time

(organic chemistry) Any trifluoro derivative of an ethyl radical, but especially CF₃CH₂-