Cerebellum refers to part of the brain coordinates body movements, controls posture, and maintains equilibrium.
Other /More definition:
Cerebellum refers to the largest part of the hindbrain.
It bulges back behind the pons varolii and the medulla oblongata, and is overhung by the occipital lobes of the cerebrum. Like the cerebrum, it has an outer grey cortex and a core of white matter.

The Cerebellum has three (3) broad bands of nerve fibres: the inferior, middle, and superior cerebellar peduncles - which connect it to the medulla, the pons varolii, and the midbrain respectively.

Cerebellum is the part of the hindbrain responsible for the coordination of voluntary muscle movement, the maintenance of balance and equilibrium, and the maintenance of muscle tone and posture; a brain structure that controls posture and balance and muscle tone, muscular/bodilycoordination, as well as some aspects of memory involving procedure-related movements; from Latin, which means "little brain".

Other functions of the Cerebellum:
1. Long Term Memory
2. Co-ordination (e.g. balance)
3. Muscle Tone
4. Movement
5. Posture

Maintenance of muscle tone, balance, and the synchronization of activity in groups of muscles under voluntary control, converting muscular contractions into smooth coordinated movement. However, it does not initiate movement and plays no part in the perception of conscious sensations or in intelligence.