Pl. tori. [L. torus a swelling, bulge, knot; muscle, brawn; bolster, cushion, couch, etc.: in Arch. a round molding.]
1. Arch. A large convex molding, of semi-circular or similar section, used especially at the base of a column: resembling the astragal, but much larger.
1563. Shute, Archit., 11. The Torus, beneth shalbe ye forth part greater then the Torus aboue.
1768. Spence, in Holdsworth, Remarks Virgil, 16. The plant which we see sometimes carved on the Torus of Pillars.
1854. H. Miller, Sch. & Schm., xiii. (1858), 271. Stairs of polished stone, ornamented in front and at the outer edge by the common fillet and torus.
1873. Proc. Amer. Phil. Soc., XIII. 210. The tori were rudely cross-barred.
2. Bot. The swollen summit of the flower-stalk, which supports the floral organs: = RECEPTACLE 3 b. THALAMUS 2 a.
1829. Loudon, Encycl. Plants (1836), 537. Sisymbrium. Silique roundish, sessile upon the torus.
1880. Gray, Struct. Bot., vi. § 1. 167. The Torus or Receptacle of the flower, also named Thalamus, is the axis which bears all the other parts.
3. a. Zool. A protuberant part or organ, as the ventral parapodia in some annelids. Torus angularis, a single ossicle which articulates with a pair of interambulacral plates in some starfishes.
b. Anat. ‘A smooth rounded ridge or elongated protuberance, as of a muscle; spec. the tuber cinereum of the brain’ (Syd. Soc. Lex.).
1877. Huxley, Anat. Inv. Anim., ix. 564. The free surface of the torus angularis lies in the walls of a sort of vestibule in front of the mouth.
4. Geom. A surface or solid generated by the revolution of a circle or other conic about any axis; e.g., a solid ring of circular or elliptic section.
1870. Cayley, Math. Papers, VII. 246. The ‘Conic Torus,’ or surface generated by the rotation of a conic about a line whether not in or in the plane of the conic. Ibid. (1871), VIII. 25. The general Torus, or surface generated by the rotation of a conic about a fixed axis anywise situate.
5. attrib. and Comb. (chiefly in sense 1).
1697. Evelyn, Archit., Misc. Writ. (1825), 378. I take a fillet to be more flat and torus-like.
1789. Gentl. Mag., Dec., 1101/2. The torus cap that bears the plinth of the balustrade.
1842. Gwilt, Archit., § 2129. The distinction between torus mouldings and beads in joinery is, that the outer edge of the former always terminates with a fillet, whether the torus be single or double.
1877. Knight, Dict. Mech., Torus Bead-plare, a certain form of plane for making the semicircular convex molding known as a torus.
