noun
(US, slang) A female teacher, especially one seen to be old-fashioned and extremely severe and strict.
(by extension) Someone who acts like a schoolmarm; a person acting harsh and stern.
(forestry) A tree with two or more trunks; a forked tree.
verb
(transitive, US, slang) To discipline in the manner of a schoolmarm; to harshly reprimand or chide.