The term SOAK TIMBER can be solved by the three letter word RET. This term is used to describe a process of treating wood with a preservative solution in order to protect it from decay and insect damage. The preservative solution is usually applied by soaking the wood in a tank or vat, which allows the preservative to penetrate deeply into the wood. This process is often used for outdoor structures such as decks, fences, and other wooden structures that are exposed to the elements.