De-activate refers to the process of stopping or turning off something. Some antonyms for this word are "activate," "energize," "power up," and "enable." These words indicate the action of starting or turning on something, rather than stopping it. Additionally, words like "ignite," "spark," and "awaken" can also be considered antonyms to de-activate, as they suggest starting or awakening something that was previously inactive. Choosing the appropriate antonym to de-activate depends on the context in which it is used. For example, activating a device versus energizing someone's spirit would require different antonyms.