Cooking weights and measures
In recipes, quantities of ingredients may be specified by mass (commonly called weight), by volume, or by count. For most of history, most cookbooks did not specify quantities precisely, instead talking of "a nice leg of spring lamb", a "cupful" of lentils, a piece of butter "the size of a small apricot", and "sufficient" salt.
Source: Wikipedia — Cooking weights and measures (CC BY-SA 4.0)