long cylindrical things such as glasses of drink, pairs of jeans, pens or trains and buses / films or TV shows / home runs or goals / rounds of a match in boxing, wrestling or judo

Alternative form of 元

book / this / main / real / actual / true

(grammar) ordinal number

preface and postscript

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

(baseball) stealing home

core of the issue / this article

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