to laugh in a silly, often high-pitched way, especially with short, repeated gasps and titters, as from juvenile or ill-concealed amusement or nervous embarrassment.
noun
2.
a silly, spasmodic laugh; titter.
3.
Slang.an amusing experience, incident, etc.: Going to a silly movie was always a giggle.
Origin: 1500–10; imitative; compare Dutchgigelen,Germangickeln. See -le