occur vs trip

occur is not a noun while trip is a noun.

Word	Noun	Adjective	Verb	Adverb
occur	No	No	Yes	No
trip	Yes	No	Yes	No

occur (noun)	trip (noun)
	a journey for some purpose (usually including the return)
	an unintentional but embarrassing blunder
	a light or nimble tread
	a catch mechanism that acts as a switch
	an accidental misstep threatening (or causing) a fall
	an exciting or stimulating experience
	a hallucinatory experience induced by drugs

occur (verb)	trip (verb)
come to pass	get high, stoned, or drugged
come to one's mind; suggest itself	put in motion or move to act
to be found to exist	miss a step and fall or nearly fall
	cause to stumble
	make a trip for pleasure