The upward force exerted by the floating body on the fluid is known as upthrust.

False, because the upward force exerted by the fluid on a fully or partially immersed object is known as upthrust force. Archimedes' principle states that when a body is completely partially submerged in a liquid or gas at rest is acted upon by an upward force which is called buoyant force or upthrust.
The magnitude of the buoyant force is equal to the weight of the fluid displaced.