chop vs chop off

chop is a noun but chop off is not a noun.

Word	Noun	Adjective	Verb	Adverb
chop	Yes	No	Yes	No
chop off	No	No	Yes	No

chop (noun)	chop off (noun)
a tennis return made with a downward motion that puts backspin on the ball
a grounder that bounces high in the air
a jaw
a small cut of meat including part of a rib
the irregular motion of waves (usually caused by wind blowing in a direction opposite to the tide)

chop (verb)	chop off (verb)
hit sharply	remove by or as if by cutting
cut with a hacking tool
cut into pieces with repeated blows
strike sharply, as in some sports
form or shape by chopping
move suddenly