DELUDED definition: entertaining a false belief or opinion; mistaken or deceived in mind or judgment. See examples of deluded used in a sentence. People are deluded if they think climate change is going to fix itself. The fact that they think their interests will be served by this shows just how deeply deluded they are. deluded in British English (dɪˈluːdɪd ) adjective believing in something that is false To cause to hold a false belief; deceive thoroughly: unscrupulous brokers who deluded their clients about the underlying value of the stocks they were touting. See Synonyms at deceive. Jan 14, 2026 · Adjective deluded (comparative more deluded, superlative most deluded) Being affected by delusions. Synonym: delusional deluded definition: believing something that is not true. Check meanings, examples, usage tips, pronunciation, domains, related words. To be deluded means to hold a belief that is not true or to be deceived by something that is not real. Being affected by delusions. He was deluded to think that she cared in the slightest. A delusion is a false fixed belief that is not amenable to change in light of conflicting evidence.