adv through.
2. thorough ·prep through.
3. thorough ·adv thoroughly.
4. thorough ·adj passing through; as, thorough lights in a house.
5. thorough ·noun a furrow between two ridges, to drain off the surface water.
6. thorough ·adj passing through or to the end; hence, complete; perfect; as, a thorough reformation; thorough work; a thorough translator; a thorough poet.