a. A knob, knot, protuberance, or swelling.
b. Medicine A small, well-defined mass of tissue that is either normal or pathological, as a lymph node or a node at an arthritic joint.
a. A point or area where two lines, paths, or parts intersect or branch off: "The nodes, or branching points, are usually demarcated by sets of one or more new, evolutionary characters that typify all taxa" (Pat Shipley).
b. A focal point or a point of interaction: "Inside the hospital, she became a node of gossip, despite being unable to communicate in the usual way" (Oliver Sacks).
a. Botany The point on a stem where a leaf is attached or has been attached; a joint.
b. See knot1.
4. Physics A point or region of virtually zero amplitude in a wave or periodic system.
5. Mathematics The point at which a continuous curve crosses itself.
6. Computers A terminal in a computer network.
a. Either of two diametrically opposite points at which the orbit of a planet intersects the ecliptic.
b. Either of two points at which the orbit of a satellite intersects the orbital plane of a planet.
[Middle English, lump in the flesh, from Latin nōdus, knot; see ned- in the Appendix of Indo-European roots.]
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