ripple vs fold up

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

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

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

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