expend vs sap

expend is not a noun while sap is a noun.

Word	Noun	Adjective	Verb	Adverb
expend	No	No	Yes	No
sap	Yes	No	Yes	No

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

expend (noun)	sap (noun)
	a piece of metal covered by leather with a flexible handle; used for hitting people
	a person who lacks good judgment
	a watery solution of sugars, salts, and minerals that circulates through the vascular system of a plant

expend (verb)	sap (verb)
use up (resources or materials)	excavate the earth beneath
pay out	deplete