The antonyms for the word "unbolts" are "bolt", "fasten", "secure", and "lock". Each of these words describes an action that is opposite to unbolt, which means to unfasten or to unlock. Bolt refers to the action of locking or fastening something securely, while fasten and secure describe actions that involve making something tight or fixed in place. Lock, on the other hand, refers to the action of using a key or combination to secure a door, window, or other opening. Knowing the antonyms for "unbolt" can help you better understand the different ways in which objects and spaces can be secured or unsecured.