yam·mer 
(yămər)Informal
(yămər)Informal v. yam·mered, yam·mer·ing, yam·mers
v.intr.
1. To talk volubly and often loudly.
2. To complain peevishly; whine: "Congress grumbled and yammered about putting up the money for the new plane" (Thomas J. Fleming).
v.tr.
To utter or say loudly or in a complaining tone.
n.
The act of yammering.
[Middle English yameren, to lament, alteration (probably influenced by Middle Dutch jammeren, to lament) of earlier Middle English yomeren, from Old English gēomrian, gēomerian, from gēomer, sad, sorrowful; akin to Old High German jāmar, perhaps ultimately of imitative origin.]
yammer·er n.