The Collaborative International Dictionary
Trimethylene
Trimethylene \Tri*meth"yl*ene\, n. (Chem.) A gaseous hydrocarbon, C3H6, isomeric with propylene and obtained from it indirectly. It is the base of a series of compounds analogous to the aromatic hydrocarbons. [1913 Webster]
Wiktionary
trimethylene
n. (context organic compound English) A gaseous hydrocarbon, C3H6, isomeric with propylene and obtained from it indirectly.