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The Collaborative International Dictionary of English v.0.48 (gcide)

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 divalent 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}.
[1913 Webster]

{Methylene blue} (Chem.), an artificial dyestuff consisting
of a complex sulphur derivative of diphenyl amine; --
called also {pure blue}.
[1913 Webster]