part name vs word

part name and word both are nouns.

Word	Noun	Adjective	Verb	Adverb
part name	Yes	No	No	No
word	Yes	No	Yes	No

As nouns, word is a hypernym of part name; that is, word is a word with a broader meaning than part name:

part name (noun)	word (noun)
a word that names a part of a larger whole	a unit of language that native speakers can identify
	a promise
	information about recent and important events
	a brief statement
	an exchange of views on some topic
	a secret word or phrase known only to a restricted group
	a verbal command for action
	a string of bits stored in computer memory

part name (verb)	word (verb)
	put into words or an expression