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

(sumo) official sumo tournament

a book published as an independent volume (as opposed to one of a series of publications)

pornographic publication (magazine, book, etc.); smut

core of the issue / this article

a surname

(chiefly Kansai) truth; reality

(slang, euphemistic) doujinshi, especially those with adult themes

a book missing a large proportion of its scrolls