Grace is in the car with her mother. they drive by a cow in a pasture, and grace says "horse." this is an example of:

Grace is in the car with her mother. they drive by a cow in a pasture, and grace says "horse." This is an example of overextension.
Overextension is part of the language development process.
It occurs when a child applies a word like “car” to all vehicles with wheels (trucks, motorcycles, and golf carts).