tref (n.)

late 13c., "wine shop," later "public house" (mid-15c.), from Old French taverne (mid-13c.) "shed made of boards, booth, stall," also "tavern, inn," from Latin taberna "shop, inn, tavern," originally "hut, shed, rude dwelling," possibly [Klein] by dissimilation from *traberna, from trabs (genitive trabis) "beam, timber," from PIE *treb- "dwelling" (source also of Lithuanian troba "a building," Old Welsh treb "house, dwelling," Welsh tref "a dwelling," Irish treb "residence," Old English ðorp "village, hamlet, farm, estate"). If so, the original meaning probably was "wooden shed."