(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)

one week

one month (duration)

a male given name

a speck; a spot / a little bit

Used other than figuratively or idiomatically: see 一 and 本 (one thing) / Short for 一本勝ち (ippon-gachi, “winning in one blow”).

solely / only, simply / alone, automatically, by itself, naturally

a female given name

a male given name