In organic chemistry, the term ethynyl designates
An ethynyl group (HC≡C–), also designated as acetylenic group (from acetylene), and referred to in IUPAC chemical nomenclature as -yne suffix. Also sometimes designed as ethinyl in compounds (ethinylestradiol, ethisterone (ethinyltestosterone)). See main page alkynes.
The ethynyl radical (HC≡C·), the compound found in interstellar medium, and transiently on earth during chemical reactions.
The ethynyl carbanion Acetylide (HC≡C−)