headshake

noun

1. the act of turning your head left and right to signify denial or disbelief or bemusement

   noun.act

   Examples

   I could tell from their headshakes that they didn't believe me.

   Synonyms headshaking

   Source: WordNet 3.0

2. A significant shake of the head, commonly as a signal of denial.

   noun

   Source: webster1913