roam vs ramble

roam is not a noun while ramble is a noun.

Word	Noun	Adjective	Verb	Adverb
roam	No	No	Yes	No
ramble	Yes	No	Yes	No

As verbs, roam and ramble are synonyms defined as:

roam and ramble: move about aimlessly or without any destination, often in search of food or employment

Other synonyms of roam include cast, drift, range, roll, rove, stray, swan, tramp, vagabond, wander.

roam (noun)	ramble (noun)
	an aimless amble on a winding course

roam (verb)	ramble (verb)
move about aimlessly or without any destination, often in search of food or employment	move about aimlessly or without any destination, often in search of food or employment
	continue talking or writing in a desultory manner