denim n.

1690s, from French serge de Nîmes "serge from Nîmes," town in southern France. Originally a kind of serge; application to "coarse, colored, twilled cotton cloth" is by 1850 in American English. Denims "pants made of denim" is recorded from 1868; originally typically overalls. The place name is Roman Nemausus, said to be ultimately from Gaulish nemo "sanctuary."