- Noun. (organic chemistry, countable) Any organic compound having one or more carbon–carbon triple bonds; an alkyne.
- Noun. (organic compound, uncountable) Ethyne; the simplest alkyne, a hydrocarbon of formula HC≡CH. It is a colourless gas, with a peculiar, unpleasant odour, formerly used as an illuminating gas, but now used in welding or metallurgy.