Rootest is a superlative form of the verb root, which means to establish deeply or firmly. Some synonyms for this word include anchor, embed, implant, ground, fix, and establish. These terms refer to the act of setting something firmly or deeply in place. The word is often used in the context of plants when referring to their ability to grow deeply into the ground, but it can also be used more generally to describe the process of establishing something firmly or securely within a particular context. Whatever the use, the synonyms for this word all point to a sense of stability, grounding, and solidity.