Here is the M. Webster Dictionary definition: Main Entry: cur·mud·geon
Pronunciation: \(ˌ)kər-ˈmə-jən\
Function: noun
Etymology: origin unknown
Date: 1568
1. (archaic) : miser
2. : a crusty, ill-tempered, and usually old man.
A curmudgeon is a person, typically an older one, who is ill-tempered, bad-tempered, cranky, or cantankerous. They are often characterized by their stubborn and irritable nature.