‘小脑’ (xiǎo nǎo) literally means ‘small brain’ and refers to the cerebellum — a major structure located at the back of the brain, beneath the cerebrum. Though smaller in size than the cerebrum, the cerebellum plays a crucial role in coordinating voluntary movements, balance, posture, and motor learning. Its name reflects its physical appearance and relative size, not its functional importance.

In medical, biological, and neuroscience contexts, 小脑 is used precisely to denote this anatomical region. It appears frequently in textbooks, clinical reports, and health education materials — for example, when discussing conditions like cerebellar ataxia or strokes affecting motor control. Unlike colloquial terms, 小脑 is strictly formal and technical; it is never used metaphorically or in casual speech to mean ‘intuition’ or ‘gut feeling’ — those ideas are expressed with other phrases like 直觉 or 下意识.