Definition:

having a smooth rich flow

Example:

"Ted Williams, a scruffy former drug addict and alcoholic, became a viral sensation this week after he was filmed by a newspaper reporter delivering lines in a mellifluous radio voice." – NineMSN.com, January 6, 2011

About the word:

Since mellifluous suggests words like "full," "sweet," and "golden," it seems appropriate that one of its ancestors is mel, Latin for "honey." (Fluous comes from fluere, "to flow.")