codimer

\(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