do·de·cyl \ˈdōdəˌsil\noun (-s) Etymology: International Scientific Vocabulary dodeca- + -yl 1.: an alkyl radical C12H25 derived from a dodecane by removal of one hydrogen atom; especially: the normal radical CH3(CH2)10CH2− 2.: a mixture of branched-chain alkyl radicals averaging C12H25 in composition — used chiefly industrially < benzene substituted by dodecyl >