Choler is a noun that refers to anger or irascibility. 

The Greek word Kholera (ko LEH rah) refers to a disease of a gastrointestinal disease. As the word entered Latin and later English, it took on a more benign form and came to refer to a person’s anger. Here’s an example:

Fred’s choler can be difficult to deal with. You have to make sure you don’t say anything to set off his short fuse.