A knife or fork with horizontal handles does not sit naturally in the curved structure of a trencher or a pottage bowl.
"soup, broth," c.1200, potage, literally "that which is put in a pot," from Old French potage "vegetable soup, food cooked in a pot," from pot "pot" (see pot (n.1)). The spelling with double -t- is from early 15c.
Heb. nazid, "boiled", a dish of boiled food, as of lentils (Gen. 25:29; 2 Kings 4:38).