| ridge resorption | A loss in the volume and size of the alveolar portion of the mandible or maxilla. (05 Mar 2000) |
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| ridgel | <zoology> Same as Ridgelling. Source: Websters Dictionary (01 Mar 1998) |
| ridgeling | <zoology> A half-castrated male animal. Origin: Prov. E. Riggilt, riggot, ananimal half castrated, a sheep having only one testicle; cf. Prov. G. Rigel, rig, a barrow hog, rigler a cock half castrated. Source: Websters Dictionary (01 Mar 1998) |
| ridiculous | 1. Fitted to excite ridicule; absurd and laughable; unworthy of serious consideration; as, a ridiculous dress or behavior. "Agricola, discerning that those little targets and unwieldy glaives ill pointed would soon become ridiculous against the thrust and close, commanded three Batavian cohorts . . . To draw up and come to handy strokes." (Milton) 2. Involving or expressing ridicule. "[It] provokes me to ridiculous smiling." (Shak) Synonym: Ludicrous, laughable, risible, droll, comical, absurd, preposterous. See Ludicrous. - Ridic"ulously, Ridic"ulousness. Origin: L. Ridiculosus, ridiculus, fr. Ridere to laigh. Cf. Risible. Source: Websters Dictionary (01 Mar 1998) |
| riding embolism | Embolism occurring at the bifurcation of an artery and blocking more or less completely both branches. Synonym: riding embolism. (05 Mar 2000) |
| Ridley's circle | Dural venous formation which surrounds the hypophysis, composed of right and left cavernous sinuses and the intercavernous sinuses. Synonym: circulus venosus ridleyi, Ridley's circle. A venous sinus at the periphery of the placenta. Synonym: sinus venosus sclerae. (05 Mar 2000) |
| Ridley's sinus | The anterior and posterior anastomoses between the cavernous sinus's, passing anterior and posterior to the hypophysis and forming, with the cavernous sinuses, the circular sinus. Synonym: sinus intercavernosi, Ridley's sinus. Jugular sinus Sinus jugularis, one of three enlargements of the jugular veins; the external jugular sinus is between the two sets of valves; the internal jugular sinus's are at the origin (superior bulb) and near the termination (inferior bulb). (05 Mar 2000) |
| Ridley, Humphrey | <person> English anatomist, 1653-1708. See: Ridley's circle, Ridley's sinus, circulus venosus ridleyi. (05 Mar 2000) |