Methylene

Part of speech: noun (n.)

A hydrocarbon radical, CH2, not known in the free state, but regarded as an essential residue and component of certain derivatives of methane; as, methylene bromide, CH2Br2; -- formerly called also methene. Methylene blue (Chem.), an artificial dyestuff consisting of a complex sulphur derivative of diphenyl amine; -- called also pure blue.