Green’s Dictionary of Slang

1. (US campus) a total failure in academic work, a grade F; thus a student who has failed.

1846		Yale Banger 10 Nov. in Hall (1856) 205: This, 0, Tutor H— said meant a perfect flunk.
1854		‘A Little More Cider’ in C. Elliot Songs of Yale (1870) 31: In spite of scrapes and flunks, I’ll have a sheep-skin too.
1856		B.H. Hall College Words (rev. edn) 205: flunk [...] a complete failure in recitation.
1871		L.H. Bagg Four Years at Yale 44: Fizzle, partial failure on recitation. Flunk, an entire failure. Both these words are also used as verbs. [Ibid.] 622: Hence, a man may skin out a whole recitation without getting any advantage from it, or sometimes may make a dead flunk instead of a rush, by reason of the instructor’s ‘skipping’ a little, and calling him up in advance of the place to which he had skinned.
1882		Harvard Crimson 22 Feb. 🌐 When he wishes to say that he has made a ‘spurt,’ or a ‘rush,’ or a ‘flunk,’ he calls upon words that would assuredly be distracting to the classic Corneille.
1896		W.C. Gore Student Sl. in Cohen (1997) 5: flunk […]7. n. A failure, particularly an entire failure.
1900		E.H. Babbitt ‘College Words and Phrases’ in DN II:i 35: flunk, n. 1. A very poor recitation. [...] 3. One who fails. [...] A failure.
1915		E. Pound letter 6–12 Sept. in Read Letters to James Joyce (1968) 45: This deluge of work by suburban counter-jumpers on the one hand and gut-less Oxford graduates or flunktuates on the other ... bah!
1927		M.C. McPhee ‘College Sl.’ in AS III:2 132: Delinquency in studies may still take the form of ‘a flunk’.
1967–8		Baker et al. CUSS 119: Flunk [...] The grade ‘F’.
1987		(con. 1967) E. Spencer Welcome to Vietnam (1989) 86: I get a call from battalion. He arrived a flunk. That’s the term for someone killed in action. Like you just didn’t make it in school.

2. attrib. use of sense 1.

1924		P. Marks Plastic Age 111: If a student failed a course, he received a ‘flunk notice’ from the registrar’s office.
1983		S. King Christine 211: Red-cards, sometimes known as flunk-cards by the student body.

3. (US) a failure.

1888		Missouri Republican 11 Feb. n.p.: Riddleberger forced the presidential possibilities of the senate to a complete flunk [F&H].
1930		G. Milburn ‘De Night Before Christmas’ in Hobo’s Hornbook 260: Yoose got no excuse / For gettin’ cold feet and goin’ down in a flunk.

4. (US) an idler, a loafer.

1890–1904

Farmer & Henley Sl. and Its Analogues.