one day

the daytime, during the day / a half day, half of a day

(rare) the first day of the month

all day, throughout the day, sunrise to sunset, all around the clock

play, amuse oneself, enjoy oneself / spend one's time idle, do nothing / for an item not to be in use, be spare or idle

studying, studies, study

to study / to discount, to reduce the price of something

Alternative form of 勉強

one day, 24 hours / the daytime, the period from dawn until dusk / (figuratively) a short period of time / one day, someday, an unspecified day / the first day of the month

(collective, chiefly attributive) Japan and China