limbic system

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A group of interconnected deep brain structures common to all mammals, including the hippocampus and amygdala, involved in olfaction, emotion, motivation, behavior, and various autonomic functions.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Anatomy, Neurophysiology) A group of neural structures in the brain below the cerebral cortex, centered on the hypothalamus and including the hippocampus and amygdala, involved with control of emotion, motivation, memory, and some homeostatic regulatory processes.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun anatomy Part of the human brain involved in emotion, motivation, and emotional association with memory; includes amygdala, cingulate gyrus, fornicate gyrus, hippocampus, hypothalamus, mammillary body, nucleus accumbens, orbitofrontal cortex and parahippocampal gyrus.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a system of functionally related neural structures in the brain that are involved in emotional behavior