Decrease is a verb that refers to the act of reducing or diminishing something. Its opposite is increase or expand, which means to add to or grow. Another opposite of decrease is surge or rise, which indicates sudden or rapid growth. To enhance or augment is another antonym for decrease, which suggests to improve or make something larger. On the other hand, to decline or weaken is another antonym for decrease, which conveys a sense of deterioration or loss. Elevate or escalate is yet another antonym for decrease, which refers to a rise or ascent in levels or quantities. Ultimately, antonyms of decrease convey a counter-directional meaning that is vital in describing an opposite effect or change.