sulcus

from WordNet (r) 3.0 (2006)

sulcus
    n 1: (anatomy) any of the narrow grooves in an organ or tissue
         especially those that mark the convolutions on the surface
         of the brain

from The Collaborative International Dictionary of English v.0.48

Sulcus \Sul"cus\, n.; pl. {Sulci}. [L., a furrow.]
   A furrow; a groove; a fissure.
   [1913 Webster]

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