knot

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Either of two migratory sandpipers of the genus Calidris that breed in Arctic regions, especially the red knot.
• noun A compact intersection of interlaced material, such as cord, ribbon, or rope.
• noun A fastening made by tying together lengths of material, such as rope, in a prescribed way.
• noun A decorative bow of ribbon, fabric, or braid.
• noun A unifying bond, especially a marriage bond.
• noun A tight cluster of persons or things.
• noun A feeling of tightness.
• noun A complex problem.
• noun A hard place or lump, especially on a tree, at a point from which a stem or branch grows.
• noun The round, often darker cross section of such a lump as it appears on a piece of cut lumber.
• noun A protuberant growth or swelling in a tissue.
• noun Nautical A division on a log line used to measure the speed of a ship.
• noun A unit of speed, one nautical mile per hour, approximately 1.85 kilometers (1.15 statute miles) per hour.
• noun A distance of one nautical mile.
• noun Mathematics A closed loop that is embedded in three-dimensional space and that can be intertwined with or tangled in itself, but that cannot intersect itself.
• intransitive verb To tie in or fasten with a knot or knots.
• intransitive verb To snarl or entangle.
• intransitive verb To cause to form a knot or knots.
• intransitive verb To form a knot or knots.
• intransitive verb To become snarled or entangled.

from The Century Dictionary.

• noun An interlacement of parts of a cord, rope, or any flexible strip, formed by twisting the ends about each other, and then drawing tight the loops thus formed; also, a similar interlacing of two or more cords, threads, etc.: a bunch of threads or thread-like things entangled together.
• noun Specifically A piece of ribbon, lace, or the like folded or tied upon itself in some particular form, used as an ornamental adjunct to a costume, or to a sword, a cane, etc.: as, a knot of ribbon; a breast-knot; a shoulder-knot.
• noun Something resembling a knot in its complication, its protuberancy, or its rounded form.
• noun The hard, cross-grained mass of wood formed in a trunk at the insertion of a branch; particularly, the round, gnarly formation resulting from a branch being broken off and the tissues growing around its stump. This stump often decays, or falls out in cutting, leaving a knot-hole.
• noun A node in a stem, or any node-like expansion in a stem, pod, etc.
• noun An excrescence on a trunk or root; a gnarl or knur.
• noun A tuft, as of grass.
• noun A flower-bud.
• noun In lithol., a small concretion or aggregation of mineral matter, or imperfectly developed crystal, found occasionally in schistose rocks, appearing to be the result of contact metamorphism. Knots of this kind sometimes occur crowded together in large numbers, so as to give a knotty appearance to what otherwise would be a quite smooth slaty surface. Such slate is called knotted slate or schist (in German knotenschiefer). The knots are sometimes simply segregations of ferruginous material around a small fragment of the slate; sometimes more or less distinctly formed crystals, andalusite being the most common mineral thus occurring. This peculiar formation is well shown in the eastern Vosges and in the lake district of England.
• noun In mech., same as knote.
• noun In architecture, same as knob.
• noun In brush-making, a tuft of bristles ready to be fastened into a hole in the stock.
• noun In anatomy, a ganglion; a node; a plexus.
• noun A defect in flint-glass, consisting of an opaque particle of earthy matter from the furnace, or abraded from the glass-pot, or a particle of glass-gall, or an imperfectly vitrified grain of sand.
• noun In physical geography, an elevated and plateau-like region where several great chains of mountains unite: a term little used by geographers except in describing parts of the chain of the Andes.
• noun Nautical: A division of the log-line, so called from the series of pieces of string stuck through the strands and knotted at equal distances on the line, being the space between any consecutive two of such knots. When the 28-second glass is used, the length of the knot is 47.3 feet. See log. A nautical mile. The length of a sea-mile varies with the latitude, according to some authorities; but the United States Hydrographic Office and United States Coast Survey have adopted 6,080.27 feet as its constant length, the English Admiralty 6,080 feet. See mile.
• noun In geometry, a universal curve in three-dimensional space, which, upon being brought into a plane by any process of distortion whatever without the crossing of one part through another (that is, without passing through a nodal form), will always have nodes or crossings. A knot differs from a link in being unicursal, while a linking consists of two curves or ovals in space, which, after being brought into a plane by the above process, are always crossed the one with the other; a lacing consists of three which are similarly joined together, independently of any linking of pairs of them. An amphichiral knot is one which is its own perversion—that is, whose image in a mirror does not differ from the knot itself in respect to right- or left-handedness.
• noun In Essex, England, eighty rounds of the reel of baize, wool, or yarn.
• noun In heraldry, a piece or two or more pieces of cord so intertwined as to form an ornamental figure. There are many forms which were in common use as badges of certain noble families in the middle ages, which have been adopted as bearings in heraldry proper.
• noun In lace-making, a small and simple ornament projecting from the outer edge of the cordonnet, a variety of the fleur-volant.
• noun Any figure the lines of which frequently intersect each other: as, a garden knot (a parterre).
• noun A cluster; a collection; a group.
• noun A swirling wave. [Rare.]
• noun A bond of association; a close union or tie: as, the nuptial knot.
• noun A difficulty, intricacy, or perplexity; something not easily solved; a puzzle.
• noun The point on which the action or development of a narrative depends; the gist of a matter; the nucleus or kernel.
• noun In hunting, one of certain morsels of flesh from the fore quarters of a stag.