Methylene \Meth"yl*ene\, n. [F. m['e]thyl[`e]ne, 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.

Source: Webster's Revised Unabridged Dictionary (1913)