thoroughprep.[See Through.] Through.(Spenser. Shak.)a.1. Passing through; as, thorough lights in a house.()2. Passing through or to the end; hence, complete; perfect; as, a thorough reformation; thorough work; a thorough translator; a thorough poet.()adv.1. Thoroughly.(Chaucer.)2. Through.(Shak.)n. A furrow between two ridges, to drain off the surface water.(Halliwell.)