"labor, toil," mid-13c., from Old French travail "work, labor, toil, suffering or painful effort, trouble; arduous journey" (12c.), from travailler "to toil, labor," originally "to trouble, torture, torment," from Vulgar Latin *tripaliare "to torture," from *tripalium (in Late Latin trepalium) "instrument of torture," probably from Latin tripalis "having three stakes" (from tria "three;" see three + palus "stake" (from PIE *pakslo-, suffixed form of root *pag- "to fasten"), which sounds ominous, but the exact notion is obscure. The verb is recorded from late 13c. in English, from the verb in Old French.

also *pak-, Proto-Indo-European root meaning "to fasten."

It forms all or part of: Areopagus; appease; appeasement; compact (adj.) "concentrated;" compact (n.1) "agreement;" fang; impact; impale; impinge; newfangled; pace (prep.) "with the leave of;" pacific; pacify; pact; pagan; page (n.1) "sheet of paper;" pageant; pale (n.) "limit, boundary, restriction;" palette; palisade; patio; pawl; pax; pay; peace; peasant; pectin; peel (n.2) "shovel-shaped instrument;" pole (n.1) "stake;" propagate; propagation; travail; travel.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit pasa- "cord, rope," pajra- "solid, firm;" Avestan pas- "to fetter;" Greek pegnynai "to fix, make firm, fast or solid," pagos "pinnacle, cliff, rocky hill;" Latin pangere "to fix, to fasten," pagina "column," pagus "district;" Slavonic paž "wooden partition;" Old English fegan "to join," fon "to catch seize."

also traveller, late 14c., agent noun from travel (v.). Traveler's check is from 1891.

"a talk on travel," 1903, a hybrid word coined by U.S. traveler Burton Holmes (1870-1958) from travel + Greek-derived -logue, abstracted from monologue.