guideword vs guide word

guideword and guide word both are nouns.

Word	Noun	Adjective	Verb	Adverb
guideword	Yes	No	No	No
guide word	Yes	No	No	No

As nouns, guideword and guide word are synonyms defined as:

guideword and guide word: a word printed at the top of the page of a dictionary or other reference book to indicate the first or last item on that page

Other synonyms of guideword include catchword.

guideword (noun)	guide word (noun)
a word printed at the top of the page of a dictionary or other reference book to indicate the first or last item on that page	a word printed at the top of the page of a dictionary or other reference book to indicate the first or last item on that page