batshit /ˈbæt.ʃɪt/noun 2adjective 1adverb 1forms 2phrases 1 noun2 •(vulgar) Fecal matter produced by bats. •(slang, vulgar) Extreme irrationality or unreasonableness, insanity, craziness.Yvette Cooper, the shadow home secretary, suggested Cleverly had previously privately referred to the Rwanda plan as “batshit”, a jibe not explicitly denied by Cleverly. — 2023 adjective1 •(slang, vulgar) Extremely irrational or unreasonable, insane, crazy.Don't take any courses from that professor. She's completely batshit. adverb1 •(slang) Used as an intensifier, particularly for insane or its synonyms.When we heard about it he went batshit nuts. formsmore batshit · most batshit Phrases with batshit go batshitTo become completely irrational; to react in an irrationally extreme manner.