1590s, "place appointed for assembling of troops," from French rendez-vous, noun use of rendez vous "present yourselves," from the wording of orders, from rendez, second person plural imperative of rendre "to present" (see render (v.)) + vous "you" (from Latin vos, from PIE *wos- "you" (plural)). General sense of "appointed place of meeting" is attested from 1590s; from c. 1600 as "a meeting held by appointment."
Old English ure "of us, pertaining to or belonging to us," genitive plural of the first person pronoun, from Proto-Germanic *ons (source also of Old Saxon usa, Old Frisian use, Old High German unsar, German unser, Gothic unsar "our"), from PIE *nes-, oblique case of personal pronoun in first person plural (source of Latin nos "we," noster "our"). Also compare ours.
Ourselves (late 15c.) "we or us, not others," modeled on yourselves, replaced original construction we selfe, us selfum, etc. It often is added to we for emphasis.