IPA: /ˈɡɪɡliər/
KK: /ˈgɪɡliər/
More inclined to giggle or laugh than usual.
She became gigglier as the funny movie went on.
Comparative: gigglier
Superlative: gigglest
'Giggle' (from Middle English 'giglen', meaning to laugh in a silly or light-hearted way) and '-ier' (a suffix used to form comparative adjectives). The word 'gigglier' means more inclined to giggle or laugh in a silly manner than someone or something else.
Think of someone who laughs in a silly way ('giggle') and remember that 'gigglier' means more likely to laugh like that.