lurk vs lurker

lurk is not a noun while lurker is a noun.

Word	Noun	Adjective	Verb	Adverb
lurk	No	No	Yes	No
lurker	Yes	No	No	No

lurk (noun)	lurker (noun)
	someone waiting in concealment

lurk (verb)	lurker (verb)
wait in hiding to attack
to monitor a web forum or similar without making your presence pubilc
be about a place without any apparent purpose
lie in wait, lie in ambush, behave in a sneaky and secretive manner