fink N. Amer.
informal
■ noun
1》 an unpleasant or contemptible person.
2》 an informer.
■ verb
1》 ( fink on ) inform on.
2》 ( fink out ) back out of a responsibility.
Origin
C19: of unknown origin; perh. from Ger., lit. 'finch', but also a pejorative term.