From Longman Dictionary of Contemporary Englishfinkfink1 /fɪŋk/ noun [countable] American English informal old-fashioned 1 TELL A SECRETsomeone who tells the police, a teacher, or a parent when someone else breaks a rule or a law2 DON'T LIKEa person who you do not like or respectfinkfink2 verb [intransitive +on] American English informal old-fashioned TELL A SECRETto tell the police, a teacher, or a parent that someone has broken a rule or a law SYN squeal on somebody→ See Verb table
Examples from the Corpus
fink• Once yer know the date an' time o' the job yer can fink back.• Mind you though, I fink it was the pipe what did it.• Besides, I fink they do a good job.• I fink they've got rid o' that chaff-cutter.Origin fink1 (1800-1900) Perhaps from German, “finch, student not belonging to a student association” 