good word vs word

good word and word both are nouns.

Word	Noun	Adjective	Verb	Adverb
good word	Yes	No	No	No
word	Yes	No	Yes	No

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

Other hypernyms of good word include intelligence, news, tidings.

good word (noun)	word (noun)
good news	a unit of language that native speakers can identify
something that recommends (or expresses commendation of) a person or thing as worthy or desirable	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

good word (verb)	word (verb)
	put into words or an expression