<chemistry> 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.

<chemistry> Methylene blue, an artificial dyestuff consisting of a complex sulphur derivative of diphenyl amine; called also pure blue.

Origin: F. Methylene, from Gr. Wine + wood; a word coined to correspond to the name wood spirit.

(01 Mar 1998)