It can mean "gossip" or the means by which gossip travels, as in the title of a Marvin Gaye hit
You can listen to the song, and read the lyrics, on this video:... [DOC] [TLE] World Wide Words: Through the grapevine [PAR] Oct 20, 2001 ... ... What does heard it through the grapevine really mean and where does it come 
from?