Demented/dɪˈmentɪd/ Definition 1 of 3Pro Tip 1/3Often Negative The word 'demented' usually describes something negative and is not a polite term to use. The way he was shouting seemed rather demented. Pro Tip 2/3Not Clinically Accurate Although 'demented' suggests insanity, it isn't a medical term when used in casual language. That demented movie plot made no sense. Pro Tip 3/3Avoid Insensitivity Using 'demented' to describe someone can be insensitive since it refers to mental health. They should have apologized for calling him demented.