Vocabulary What does 何歳 (なんさい, nansai) mean? 何歳 (なんさい, nansai) means how old; what age. Quick factsReadingなんさいRomajinansaiPart of speechnoun 何歳なんさいnansaihow old; what age1noun how old; what ageAlso written: 何才Kanji in this word何what歳years of age; year