The word "re-strain" means to hold back, restrict or limit something. Its antonyms include words like "liberate," "release," "free," "ungag," "unbind," "loosen," "unfetter," "let go," "uncage," "unleash" and "unshackle." All these words convey the opposite meaning of "re-strain," suggesting the removal of restraints or constraints. Their use can be appropriate in various contexts, such as in discussions on personal or societal freedoms, physical or mental limitations, creative expression, and more. Effective communication demands a vast vocabulary, and employing the right antonyms can precisely convey the message one wants to send.