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/nohd/, n.1. a knot, protuberance, or knob.2. a centering point of component parts.3. Anat. a knotlike mass of tissue: lymph node.4. Pathol. circumscribed swelling.5. Bot.a. a joint in a stem.b. a part of a stem that normally bears a leaf.6. Math. knot (def. 12).7. Geom. a point on a curve or surface at which there can be more than one tangent line or tangent plane.8. Physics. a point, line, or region in a standing wave at which there is relatively little or no vibration.9. Astron. either of the two points at which the orbit of a heavenly body intersects a given plane, esp. the plane of the ecliptic or of the celestial equator. Cf. ascending node, descending node.10. Ling. an element of a tree diagram that represents a constituent of a linguistic construction.11. Optics. See nodal point.12. Engin. See panel point.13. nodus.[1565-75; < L nodus knot]
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in astronomy, the intersection of the orbit plane of some celestial body, such as the Moon, a planet, or comet, with the plane of the ecliptic (the apparent path of the Sun among the stars) as projected on the celestial sphere. The ascending node is the one where the body crosses from the south to the north side of the ecliptic, the opposite one being the descending node. An eclipse of the Sun or Moon can occur only when the Moon is at or near a node; similarly, only when one of the inner planets is at or near a node can it appear in transit across the Sun. See also orbit.* * *
Universalium. 2010.
