To make someone or something seem foolish by laughing at them or copying them in an unkind way.
The other students ridiculed him for his mistake.
The article ridiculed the mayor's plan.
Ridicule is stronger than simply laugh at: it means trying to make someone look foolish.
Common phrases & grammar
publicly ridicule someone · ridicule an idea · ridicule someone for a mistake
ridicule + someone/something
ridicule + someone + for + noun/-ing