part of brain 1: The portion of the vertebrate central nervous system that constitutes the organ of thought and neural coordination, includes all the higher nervous centers receiving stimuli from the sense organs and interpreting and correlating them to formulate the motor impulses, is made up of neurons and supporting and nutritive structures, is enclosed within the skull, and is continuous with the spinal cord through the foramen magnum. Also named encephalon. 2: A nervous center in invertebrates comparable in position and function to the vertebrate brain. BTO:0000142 BrendaTissueOBO encephalon central nervous system head