the daytime, during the day / noon, midday

Saturday

(rare) a birthday

a lucky day, auspicious day

(rare) one's birthday

the first day of the month (solar or lunar calendar)

(obsolete) one day, 24 hours / (obsolete) the daytime, the period from dawn until dusk

(rare, obsolete) (all senses appear to be identical as for hitohi above)

(literary) one day, 24 hours / (literary) the daytime, the period from dawn until dusk / (literary) (figuratively) a short period of time

the fifteenth day of a month in the lunar calendar