Entry 6 senses · 4 variants Webster, 1913 Thorough /thẽr'-ō/ · Thor·ough · IPA /ˈθʌɹoʊ/ prep. a. adv. n. 01 prep. Through. 1. Through.[Obs.] 02 a. Passing through; as, thorough lights in a house. 1. Passing through; as, thorough lights in a house.[Obs.] 2. Passing through or to the end; hence, complete; perfect; as, a thorough reformation; thorough work; a thorough translator; a thorough poet. 03 adv. Thoroughly. 1. Thoroughly.[Obs. or Colloq.] 2. Through.[Obs.] 04 n. A furrow between two ridges, to drain off the surface water. 1. A furrow between two ridges, to drain off the surface water.[Prov. Eng.]