Webster's Revised Unabridged Dictionary · 1913

Giggle

Giggle , transitive verb

[Akin to gaggle: compare OD. ghichelen, German kichern.]

To laugh with short catches of the breath or voice; to laugh in a light, affected, or silly manner; to titter with childish levity.
Giggling and laughing with all their might At the piteous hap of the fairy wight. — J. R. Drake

Giggle , noun

A kind of laugh, with short catches of the voice or breath; a light, silly laugh.