Originally: (Mathematics) designating a proportion between two pairs of quantities in which the ratio of one pair is equal to the ratio of the sixth powers of the other pair, and one between two variable quantities in which one has a constant ratio to the sixth power of the other (now historical). Later: (more generally) sixfold; sextuple; consisting of six identical or similar things.
Each of six things exactly alike or closely resembling one another.
Mid 17th century; earliest use found in Thomas Hobbes (1588–1679), philosopher. From post-classical Latin sextuplicatus sixfold, probably from classical Latin sextus sixth + -uplicātus (in quadruplicātus); compare post-classical Latin sextuplic-, sextuplex.