kitchen appliance used for baking or roasting
"She preheated the oven to bake a batch of cookies."
A chamber used for baking or heating.
"The baker placed the loaf of bread into the hot oven to ensure it baked evenly."
In plain English: An oven is an appliance that uses heat to cook food inside its enclosed space.
"She preheated the oven before baking the cookies."
The word "oven" comes directly from the Old English term for a heated enclosure used to bake food. It has remained in use with virtually no change in meaning since its earliest recorded history.