titter

verb (used without object)

1. to laugh in a restrained, self-conscious, or affected way, as from nervousness or in ill-suppressed amusement.

noun

2. a tittering laugh.

verb

1. (intr) to snigger, esp derisively or in a suppressed way
2. (tr) to express by tittering

noun

3. a suppressed laugh, chuckle, or snigger

v.1610s, “giggle in a suppressed or covert way,” probably of imitative origin. Related: Tittered; tittering. The noun is first recorded 1728.