giggle (v.)youdaoicibaDictYouDict[giggle 词源字典]
c. 1500, probably imitative. Related: Giggled; giggling; giggly. As a noun from 1570s. [giggle etymology, giggle origin, 英语词源]
titillation (n.)youdaoicibaDictYouDict
early 15c., "pleasing excitement," from Latin titillationem (nominative titillatio) "a tickling," noun of action from past participle stem of titillare "to tickle," imitative of giggling.