As nouns: A rumour is one story or report of unverified information. Gossip is the conversation or sum of reports or stories.
Have you heard the rumour about Mickey Mouse? *** One specific story or report
Have you heard the rumours about Mickey Mouse? *** Multiple stories or reports
Have you heard the gossip about Mickey Mouse? *** All of the rumours, even if there is only one rumour
As verbs: Gossip means to participate in the conversation of gossip. Rumour in verb form generally appears as "rumoured", and it means the story or report is being spread , distributed, or circulated.
Donald Duck likes to gossip about Mickey Mouse. ***Donald likes to talk about rumours about Mickey
It is rumoured that Mickey Mouse likes Minnie Mouse. ***Rumours have spread and are spreading about that Mickey likes Minnie
Also, "Rumour has it" = the unverified report/story is...
Rumour has it that Mickey likes Minnie.