methylene n.

"a strong liquor made from fermented honey and water," a favorite beverage of England in the Middle Ages, Middle English mede, from Old English medu, from Proto-Germanic *meduz (source also of Old Norse mjöðr, Danish mjød, Old Frisian and Middle Dutch mede, Old High German metu, German Met "mead"), from PIE root *medhu- "honey, sweet drink" (source also of Sanskrit madhu "sweet, sweet drink, wine, honey," Greek methy "wine," Old Church Slavonic medu, Lithuanian medus "honey," Old Irish mid, Welsh medd, Breton mez "mead"). Synonymous but unrelated early Middle English meþeglin yielded Chaucer's meeth.

chemical suffix used in forming names of radicals, from French -yle, from Greek hylē "wood," also "building stuff, raw material" (from which something is made), of unknown origin. The use in chemistry traces to the latter sense (except in methylene, where it means "wood").

It was introduced into chemical nomenclature by Liebig and Wohler when, in 1832, they used the term benzoyle for the radical which appeared to be the "essential material" of benzoic acid and related compounds. [Flood]