muff vs screw up

muff is a noun but screw up is not a noun.

Word	Noun	Adjective	Verb	Adverb
muff	Yes	No	Yes	No
screw up	No	No	Yes	No

As verbs, muff and screw up are synonyms defined as:

muff (noun)	screw up (noun)
(sports) dropping the ball
a warm tubular covering for the hands

muff (verb)	screw up (verb)
make a mess of, destroy or ruin	twist into a strained configuration
fail to catch, as of a ball	make more intense
	screw or turn higher
	make a mess of, destroy or ruin