A measure of the responsiveness of quantity demanded or quantity supplied to a change in price is known as
The term that you are looking for here is elasticity. More specifically, it is price elasticity of demand (and price elasticity of supply).
The law of demand says that, when the price of a good or service goes up, the quantity demanded of that product will go down. However, it does not say how much it will go down. If, for example, people buy 1 million TVs when a TV costs $200, how many will they buy when the price goes up to $220? Will they buy 990,000 or 900,000? The amount that the quantity demanded goes down (how much quantity demanded responds to the change in price) is called elasticity. The more the quantity demanded changes, the more elastic the demand for the product is.
The same dynamic holds for supply, only with the relationship reversed. When the price for which a product can be sold goes up, quantity supplied will also go up. There is still, however, the question of how much it will go up. If the quantity supplied goes up a lot when the price rises, we say the supply is elastic. If it only goes up a little, we say the supply is relatively inelastic.
Thus, the answer you are looking for is price elasticity of demand and supply.