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.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2019 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.