(1):

(adv.) Thoroughly.

(2):

(adv.) Through.

(3):

(a.) Passing through; as, thorough lights in a house.

(4):

(prep.) Through.

(5):

(n.) A furrow between two ridges, to drain off the surface water.

(6):

(a.) Passing through or to the end; hence, complete; perfect; as, a thorough reformation; thorough work; a thorough translator; a thorough poet.