rumor vs scuttlebutt

rumor and scuttlebutt both are nouns.

Word	Noun	Adjective	Verb	Adverb
rumor	Yes	No	Yes	No
scuttlebutt	Yes	No	No	No

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

rumor: gossip (usually a mixture of truth and untruth) passed around by word of mouth
scuttlebutt: a report (often malicious) about the behavior of other people

Other hypernyms of rumor include comment, gossip.

rumor (noun)	scuttlebutt (noun)
gossip (usually a mixture of truth and untruth) passed around by word of mouth	a report (often malicious) about the behavior of other people

rumor (verb)	scuttlebutt (verb)
tell or spread rumors