of or having to do with a single source that controls all activity in an organization or system
designating or of that part of a nervous system consisting of the brain and spinal cord or, in many invertebrates, the chief ganglia and their major nerve cords
of the centrum of a vertebra
Phonet. articulated with the tongue in a position approximately halfway between front and back: said of certain vowels, as (u) in bud
noun
a telephone exchange, esp. the main one, or the telephone operator: an early term