To jeer means to shout mocking, mean-spirited remarks at someone, usually in a crowd. When fans jeer at an opposing team's player, they might yell insults or boo loudly to rattle the player's confidence. When someone jeers at a performer, they're actively trying to embarrass or upset them with cruel words and hostile shouts.

Jeering is nastier than ordinary booing. A crowd might boo a referee's bad call but jeer at a player they genuinely dislike. The word carries a sense of contempt and ridicule. Think of the difference between politely saying “I disagree” and laughing mockingly at someone's idea while pointing and making fun of them.

Sometimes people jeer because they're caught up in crowd mentality, saying things they might never say alone. In stories about ancient Rome, crowds would jeer at gladiators or prisoners. Today, jeering still happens at sporting events or political rallies, though it reveals more about the people doing the jeering than about their targets.

As a noun, a jeer is one of those mocking shouts: “The player ignored the jeers from the stands and focused on the game.”