The phrase "knock cold" means to render someone unconscious or incapacitated. Some antonyms for this expression include awaken, revive, energize, stimulate, and vitalize. These words imply a renewal of consciousness and vitality, rather than a loss of it. Other antonyms for "knock cold" include rally, recuperate, recover, and bounce back, which all indicate a return to a normal state of health and function. These antonyms may be useful in situations where a person needs to be revived or rejuvenated, rather than subdued or incapacitated. Understanding antonyms is an essential part of building a strong vocabulary and communicating effectively.