IPA: /ˈkʊk.tɒp/
KK: /ˈkʊkˌtɑp/
A flat surface used for cooking, typically found on a stove or built into a countertop, which often has electric heating elements.
She prepared dinner on the cooktop while chatting with her friend.
Cooktop is formed from "cook" (from Old English "coc", meaning to prepare food) and "top" (from Old English "top", meaning the highest point or surface). The word "cooktop" refers to the surface area where cooking is done, typically on a stove.
Think of a 'cook' preparing food on the 'top' surface of a stove — that's what a cooktop is.
No commonly confused words.