stab vs knife

stab and knife both are nouns.

Word	Noun	Adjective	Verb	Adverb
stab	Yes	No	Yes	No
knife	Yes	No	Yes	No

As verbs, stab and knife are synonyms defined as:

stab (noun)	knife (noun)
a strong blow with a knife or other sharp pointed instrument	edge tool used as a cutting instrument; has a pointed blade with a sharp edge and a handle
informal words for any attempt or effort	a weapon with a handle and blade with a sharp point
a sudden sharp feeling	any long thin projection that is transient