Simple past tense and past participle of titter.(verb)
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Use "tittered" in a sentence
"A couple of the women tittered as they gamely joined in."
"Mrs. Schoville tittered and thought it all so unique, and she thought it so unique several times more when the lieutenant of Mounted Police and a couple of compatriots roared Rule"
"The dancers tittered on the tiptoes of expectancy."