Why is the ninth month called September?
c.1500, "old experienced soldier," from French vétéran, from Latin veteranus "old," from vetus (genitive veteris) "old," from PIE *wetus- "year" (cf. Sanskrit vatsa- "year," Greek etos "year," Hittite witish "year," Old Church Slavonic vetuchu "old," Old Lithuanian vetušas "old, aged"). Latin vetus also is the ultimate source of Italian vecchio, French vieux, Spanish viejo. General sense of "one who has seen long service in any office or position" is attested from 1590s. The adjective first recorded 1610s.