Vocabulary What does 大晦日 (おおみそか, oomisoka) mean? 大晦日 (おおみそか, oomisoka) means New Year's Eve. Quick factsReadingおおみそかRomajioomisokaPart of speechnoun 大晦日おおみそかoomisokaNew Year's Eve1noun New Year's EveAlso written: 大みそかKanji in this word大big, large日day; sun