sharpen vs strop

sharpen is not a noun while strop is a noun.

Word	Noun	Adjective	Verb	Adverb
sharpen	No	No	Yes	No
strop	Yes	No	Yes	No

As verbs, strop is a hyponym of sharpen; that is, strop is a word with a more specific, narrower meaning than sharpen:

Other hyponyms of sharpen include strap, edge, whet, hone.

sharpen (noun)	strop (noun)
	a leather strap used to sharpen razors

sharpen (verb)	strop (verb)
become sharp or sharper	sharpen on a strop
make crisp or more crisp and precise
raise the pitch of (musical notes)
put (an image) into focus
make (one's senses) more acute
give a point to
make sharp or sharper
make (images or sounds) sharp or sharper