sul·cus /ˈsʌlkəs/
  溝; 胼胝體溝; 凹; 槽
  sul·cus /ˈsəlkəs/ 名詞
  (複sulci)溝,牙齒咬合面的線狀凹陷,其斜邊成角相交,溝,牙齒咬合面的淺狀凹陷
  Sul·cus n.; pl. Sulci   A furrow; a groove; a fissure.
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  sulcus
       n : (anatomy) any of the narrow grooves in an organ or tissue
           especially those that mark the convolutions on the
           surface of the brain
       [also: sulci (pl)]