A Definition

ru·mor

Pronunciation: \ˈrü-mər\

Function: noun

Etymology: Middle English rumour, from Anglo-French, from Latin rumor clamor, gossip; akin to Old English rēon to lament, Sanskrit rauti he roars

1: talk or opinion widely disseminated with no discernible source
2: a statement or report current without known authority for its truth

[My emphasis]

Source: Merriam-Webster Online Dictionary