|Origin:||Perhaps from flinch + funk 'to be afraid (of)' (18-21 centuries); FUNK2|
flunk informal especially American English
1 [intransitive and transitive]SE
to fail a test:
Tony flunked chemistry last semester.
to give someone low marks on a test so that they fail it [= fail]:
She hadn't done the work so I flunked her.
flunk outphrasal verb
to be forced to leave a school or college because your work is not good enough
flunk out of
Ben flunked out of college.