(ˈ)kō|dīmə(r) noun
( -s )
Etymology: co- + dimer
: a copolymer formed from two dissimilar molecules (as two olefins) ; specifically in petroleum refining : the mixture of hydrocarbons formed by the copolymerization of the butylenes which on hydrogenation yields a mixture of octanes used as a blending agent in aviation gasoline