undertake vs subcontract

undertake is not a noun while subcontract is a noun.

Word	Noun	Adjective	Verb	Adverb
undertake	No	No	Yes	No
subcontract	Yes	No	Yes	No

undertake (noun)	subcontract (noun)
	a contract assigning to another party some obligations of a prior contract

undertake (verb)	subcontract (verb)
promise to do or accomplish	work under a subcontract; engage in a subcontract
enter into a contractual arrangement	arranged for contracted work to be done by others
enter upon an activity or enterprise
accept as a charge
accept as a challenge