sulcus
Concise Oxford English Dictionary © 2008 Oxford University Press:
sulcus /ˈsʌlkəs/
▶noun (pl. sulci /-sʌɪ/) Anatomy a groove or furrow, especially one on the surface of the brain.
– origin C17: from L., ‘furrow, wrinkle’.
'sulcus' also found in these Oxford entries:

