IPA: /ˈtɑːrt.nəs/
KK: /tɑrt.nəs/
The quality of having a sharp, sour, or acidic taste.
The tartness of the lemon made the pie very refreshing.
Tartness → It is formed from "tart" (from Old French *tart*, meaning sharp or sour) and "-ness" (meaning the state or quality of). The word "tartness" refers to the quality of being sharp or sour in taste.
Think of the word 'tart' which means sharp or sour, and remember that 'tartness' describes the quality of having that sharp or sour taste.