dander

In a biological sense, this term refers to the microscopic skin scales shed by animals. It is distinct from dandruff, which specifically refers to the human scalp, though the two are physiologically similar. In veterinary and allergy contexts, it is treated as a mass noun representing the collective particulate matter.

When used to describe a person's mood, the word appears almost exclusively in the idiomatic phrase "get one's dander up." This usage is colloquial and carries a tone of sudden, prickly irritation or indignation rather than deep-seated rage. It evokes an image of bristling or becoming agitated, similar to how an animal's fur might stand up when threatened.