ニコニコ Common word JLPT N2 LinksSentence search for ニコニコSentence search for にこにこEdit in JMdict Adverb (fukushi), Adverb taking the 'to' particle, Suru verb1. with a friendly grin; smilinglyOnomatopoeic or mimetic wordOther formsにこにこ Discussions Log in to talk about this word.