Contemptuous exclamation (3)
I believe the answer is:
bah
(Other definitions for bah that I've seen before include "Exclamation of contempt or disgust - Scrooge used to say it" , "Exclamation of disgust or annoyance" , "''... Humbug'' Scrooge's cry" , "''...! Humbug!'' (Scrooge)" , "Appalling!" .)