[1] : WordNet (r) 2.0

grey substance
     n : greyish nervous tissue containing cell bodies as well as
         fibers; forms the cerebral cortex consisting of
         unmyelinated neurons syn: grey matter, gray matter,
         gray substance, substantia grisea
see also:
grey matter gray matter gray substance substantia grisea 

Substance >> S Words
Substance, definition of term: Substance
substance_pag1.html

Grey >> G Words
Grey, definition of term: Grey
grey_pag1.html

Substance Abuse >> S Words
Substance Abuse, definition of term: Substance Abuse
substance+abuse_pag1.html

Grey Matter >> G Words
Grey Matter, definition of term: Grey Matter
grey+matter_pag1.html