through
adj.adj. describes a route or a ticket that goes from the start to the finish without any changes or stops. You might take a through train to get somewhere directly.
adj. permitting uninterrupted passage or travel from an origin to a destination. Typically used as an attributive adjective before a noun.
This bus is a through service to the airport.
We bought through tickets from our town to the capital, so we don't have to change trains.
Planners redesignated the quiet residential street as a through road, increasing traffic volume and prompting safety complaints from residents accustomed to the previously quiet environment.
From Middle English thrugh, thruch, thruh, metathetic variants of thurgh, thurh, from Old English þurh, from Proto-Germanic þurhw (“through”), from Proto-Indo-European tr̥h₂kʷe, suffixed zero-grade from terh₂- (“to pass through”) + -kʷe (“and”). Cognates Cognate with North Frisian döör (“through”), Saterland Frisian truch (“through”), West Frisian troch (“through”), Dutch door (“through”), German durch (“through”), Luxembourgish duerch (“through”), West Flemish deur (“through”), Yiddish דורך (durkh, “through”), Gothic 𐌸𐌰𐌹𐍂𐌷 (þairh, “through”), Latin trans (“across, over, through”), Albanian tërthor (“through, around”), Welsh tra (“through”). See also thorough.
From Middle English thrugh, þrouȝ, throgh, from Old English þrūh (“trough, conduit, pipe; box, chest; coffin, tomb”), from Proto-Germanic þrūhs (“excavated trunk, trough”), from Proto-Indo-European terh₃u- (“to rub, turn, drill, bore”).