sinus
n. (உள்., வில.) எலும்பு உட்புழை, பைக்குழிவு, (மரு.) புண்ணின் உட்புரை, (மரு.) பிளவை, குறுவாயுடைய புரையோடிய புண், (தாவ.) இலையோரப் பிரிவுகளிடைப்பட்ட உள்வளைவு.
Si"nus, n.; pl. L. Sinus, E. Sinuses. Etym: [L., a bent surface, a curve, the folds or bosom of a garment, etc., a bay. Cf. Sine, n.] 1. An opening; a hollow; a bending. 2. A bay of the sea; a recess in the shore. 3. (Anat. & Zoöl.) Defn: A cavity; a depression. Specifically: (a) A cavity in a bone or other part, either closed or with a narrow opening. (b) A dilated vessel or canal. 4. (Med.) Defn: A narrow, elongated cavity, in which pus is collected; an elongated abscess with only a small orifice. 5. (Bot.) Defn: A depression between adjoining lobes. Note: A sinus may be rounded, as in the leaf of the white oak, or acute, as in that of the red maple. Pallial sinus. (Zoöl.) See under Pallial. -- Sinus venosus. Etym: [L., venous dilatation.] (Anat.) (a) The main part of the cavity of the right auricle of the heart in the higher vertebrates. (b) In the lower vertebrates, a distinct chamber of the heart formed by the union of the large systematic veins and opening into the auricle.