grey matter grey·mat·ter uncommon noun 1. greyish nervous tissue containing cell bodies as well as fibers; forms the cerebral cortex consisting of unmyelinated neurons Synonymsgrey mattergray mattergrey substancegray substancesubstantia grisea Related words Broader terms nervous tissue Parts cerebral cortex WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.
