Know how to use "fewer" and "less"? Find out.
mid-15c., as an adverb, "together, at the same time," from Middle French ensemblée "all the parts of a thing considered together," from Late Latin insimul "at the same time," from in- intensive prefix + simul "at the same time," related to similis (see similar). The noun is from 1703, "parts of a thing taken together;" musical sense in English first attested 1844. Of women's dress and accessories, from 1927.