1560s (attested in Anglo-Latin from late 13c.), from Late Latin itinerantem (nominative itinerans), present participle of itinerare "to travel," from Latin iter (genitive itineris) "a journey," from ire "go" (from PIE root *ei- "to go"). Originally in reference to circuit courts. As a noun from 1640s. Related: Itinerancy. Middle English had itineral "having to do with travel" (late 15c.).