fink vs rat

fink and rat both are nouns.

Word	Noun	Adjective	Verb	Adverb
fink	Yes	No	Yes	No
rat	Yes	No	Yes	No

As nouns, rat is a hypernym of fink; that is, rat is a word with a broader meaning than fink:

fink: someone acting as an informer or decoy for the police
rat: one who reveals confidential information to the police or other authority

Other hypernyms of fink include betrayer, blabber, informer, squealer.

As verbs, fink and rat are synonyms defined as:

Other synonyms of fink include blackleg, scab.

fink (noun)	rat (noun)
someone acting as an informer or decoy for the police	any of various long-tailed rodents similar to but larger than a mouse
	a pad (usually made of hair) worn as part of a woman's coiffure
	a person who is deemed to be despicable or contemptible
	someone who works (or provides workers) during a strike
	one who reveals confidential information to the police or other authority

fink (verb)	rat (verb)
confess to a punishable or reprehensible deed, usually under pressure	give away information about somebody
take the place of work of someone on strike	catch rats, especially with dogs
	give (hair) the appearance of being fuller by using a rat
	desert one's party or group of friends, for example, for one's personal advantage
	take the place of work of someone on strike
	employ scabs or strike breakers in