gag

Concise Oxford English Dictionary © 2008 Oxford University Press:
gag1

▶noun

• 1 a piece of cloth put in or over a person's mouth to prevent them from speaking.

• 2 a device for keeping the patient's mouth open during a dental or surgical operation.

• 3 a restriction on free speech.

▶verb (gags, gagging, gagged)

• 1 put a gag on.

  ■ prevent from speaking freely.

• 2 choke or retch.

– origin ME: perh. rel. to ON gagháls ‘with the neck thrown back’, or imitative of a person choking.

Concise Oxford English Dictionary © 2008 Oxford University Press:
gag2

▶noun a joke or funny story, especially one forming part of a comedian's act. ▶verb tell jokes.

– origin C19 (orig. theatrical sl.): of unknown origin.