Definitions
1.nounAny organic compound having one or more carbon–carbon triple bonds; an alkyne.
2.nounEthyne; the simplest alkyne, a hydrocarbon of formula HC≡CH. It is a colourless, odorless gas, formerly used as an illuminating gas, but now used in welding or metallurgy.
3.nounA lamp powered by acetylene, particularly a motor vehicle headlight.