fold up vs ripple

fold up is not a noun while ripple is a noun.

Word	Noun	Adjective	Verb	Adverb
fold up	No	No	Yes	No
ripple	Yes	No	Yes	No

fold up (noun)	ripple (noun)
	a small wave on the surface of a liquid
	(electronics) an oscillation of small amplitude imposed on top of a steady value

fold up (verb)	ripple (verb)
become folded or folded up	stir up (water) so as to form ripples
bend or lay so that one part covers the other	flow in an irregular current with a bubbling noise