late 14c., "to journey," from travailen (1300) "to make a journey," originally "to toil, labor" (see travail). The semantic development may have been via the notion of "go on a difficult journey," but it also may reflect the difficulty of any journey in the Middle Ages. Replaced Old English faran. Related: Traveled; traveling. Traveled (adj.) "having made journeys, experienced in travel" is from early 15c. Traveling salesman is attested from 1885.
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<a href="https://www.etymonline.com/word/traveler">Etymology of traveler by etymonline</a>
Harper, D. (n.d.). Etymology of traveler. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/traveler