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]

by 1879, U.S. dialect abbreviation of you all (see you, and compare yins).

Children learn from the slaves some odd phrases ... as ... will you all do this? for, will one of you do this? ["Arthur Singleton" (Henry C. Knight), "Letters from the South and West," 1824]

We-all for "us" is attested by 1865; we-uns by 1864. Who-all attested from 1899.