noun
gray matter; grey matter
Anatomical term for the grayish nerve tissue of the brain and spinal cord.
脳の灰白質は神経細胞の集まりだ。
The brain's gray matter is a collection of nerve cells.
白質 (white matter) is the counterpart to 灰白質, referring to the paler nerve tissue mainly composed of myelinated axons.
Compound of 灰白 (かいはく, 'grayish white') and 質 (しつ, 'substance, quality'). The term is a direct calque from Western anatomical terminology.