IPA: /ˈtɑrtli/
KK: /tɑrtli/
In a way that is sharp or sour in taste or tone; often used to describe a biting or cutting remark.
She replied tartly when asked about her opinion on the matter.
Tartly → It is formed from "tart" (from Old French *tart*, meaning sharp or sour) and "-ly" (meaning in a manner of). The word "tartly" means in a sharp or sour manner, often referring to a tone or manner of speaking.
Think of the word 'tart' which means sharp or sour, and remember that 'tartly' describes doing something in a sharp or sour way.