At a party last spring, we watched two colleagues argue over who would make the first toast to the host. One said, “I’ll make the toast since I’ve known her the longest.” The other rolled her eyes and said under her breath, but loud enough for many to hear, “You’re such a narcissist!” The word “narcissist” echoed as a hush fell over the room.

This incident offers an example of how carelessly — and often inaccurately — people use powerful words. We have heard countless people misuse similarly strong terms: