The word "un-loosened" means something which is fixed or secured. The antonyms for "un-loosened" can be "loosened," "unfastened," "released," "untied," or "unclenched." When something is loosened, it becomes free and relaxed. Unfastened means the opposite of fastened, and when something is unfastened, it becomes open and free. When something is released, it means it is let go, and untied means to undo a knot or bond. Lastly, unclenched represents the relaxing or releasing of a hand or another body part. All of these words, being antonyms for "un-loosened," all carry the meaning of freeing or unlocking something.