A centre of intellectual or industrial force, activity, etc.
An encapsulated collection of nerve cell bodies, typically linked by synapses, and often forming a swelling on a nerve fiber.
Any of certain masses of gray matter in the central nervous system, as the basal ganglia.
A benign cystic tumour on a tendon sheath or joint capsule.
The basic inner workings of something; the fundamentals; that which makes something operate.