noun / verb
titter
TIT-er/tˈɪtɝ/
A quiet, nervous or silly laugh.
A nervous titter breaks the silence when she forgets her lines.

Etymology
The verb is probably an imitation of the sound of a suppressed giggle. Its recorded meaning already includes restrained or nervous laughter.
More examples
- The children titter whenever the teacher says the silly name.
- A few embarrassed titters followed his awkward joke.
- She tittered behind her hand during the serious speech.
Forms
titter · titters · tittered · tittering