the sixth day of the month / six days

the fourth day of the month / four days

the third day of the month / three days

the tenth day of the month / ten days

two days, a two-day period / the second day after some set point in time / the second day of the month

(physics) fundamental interaction

(geography) a prime meridian

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

a comic book, a cartoon book

hardcore pornography; 'underground' pornography showing uncensored genitals. Technically illegal in Japan.