current, this, the matter in question / original, actual, base

book / this / main / real / actual / true

stairs used in emergencies

state of emergency (unusually difficult or dangerous situation)

state of emergency (governmental decree)

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.

banned book

a male given name / a male given name