一日

いちにち · いちじつ also １日

1. noun, adverb one day
2. adverb, noun all day (long); the whole day; from morning till night
3. noun first day of the month

ついたち also １日

1. noun first day of the month; the first of the month

つきたち also 月立ち · 月立 · 朔

1. noun, archaic first day of the month
2. first ten days of the lunar month

ひとひ

1. noun, adverb, dated one day
2. adverb, noun, dated all day (long); the whole day
3. noun, poetic 1st day of the month

いっぴ

1. noun, used mainly in business first day of the month