The word "pressurize" means the act of applying pressure to something or someone. A few antonyms for the word "pressurize" can be identified, such as relax, ease, alleviate, relieve, and calm. Relax means to make someone or something less tense, while ease refers to making something less difficult or troublesome. Alleviate means to make something less severe, and relieve refers to eliminating pain or discomfort. Lastly, calm means to make someone or something peaceful or serene. All these words describe opposite actions to "pressurize" which is adding pressure, stress, or tension to someone or something.