Meth″yl‐ene (?), n. [F. méthylène, from Gr. � wine + � wood; — a word coined to correspond to the name wood spirit.] (Chem.) 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.