from The American Heritage® Dictionary of the English Language, 4th Edition

  • adj. Making contact at a single point or along a line; touching but not intersecting.
  • adj. Irrelevant.
  • n. A line, curve, or surface meeting another line, curve, or surface at a common point and sharing a common tangent line or tangent plane at that point.
  • n. Mathematics The trigonometric function of an acute angle in a right triangle that is the ratio of the length of the side opposite the angle to the length of the side adjacent to the angle.
  • n. A sudden digression or change of course: went off on a tangent during the courtroom argument.
  • n. Music An upright pin in a keyboard instrument, especially in a clavichord, that rises to sound a string when a key is depressed and stops the string at a preset length to set the pitch.

from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. A straight line touching a curve at a single point without crossing it there.
  • n. In a right triangle, the ratio of the length of the side opposite the angle to the length of the side adjacent to the angle. Symbols: tan, tg
  • n. A topic nearly unrelated to the main topic, but having a point in common with it.
  • n. A small metal blade by which a clavichord produces sound.
  • adj. Touching a curve at a single point but not crossing it at that point.
  • adj. Of a topic, only loosely related to a main topic.

from the GNU version of the Collaborative International Dictionary of English

  • adj. Touching; touching at a single point.
  • n. A tangent line curve, or surface; specifically, that portion of the straight line tangent to a curve that is between the point of tangency and a given line, the given line being, for example, the axis of abscissas, or a radius of a circle produced. See Trigonometrical function, under function.

from The Century Dictionary and Cyclopedia

  • Touching; in geometry, touching at a single point: as, a tangent line; curves tangent to each other.
  • n. In geometry: A straight line through two consecutive points (which see, under consecutive) of a curve or surface.
  • n. The length cut off upon the straight line touching a curve between the line of abscissas and the point of tangency.
  • n. In trigonometry, a function of an angle, being the ratio of the length of one leg of a right triangle to that of the other, the angle opposite the first leg being the angle of which the tangent is considered as the function.
  • n. In the clavichord, one of the thick pins of brass inserted in the back ends of the digitals so that the fingers should press them against the strings, and produce tones.
  • n. Any method of drawing a tangent to a curve.
  • To bear or hold the relation of a tangent to.
  • n. One of the keys or finger-levers of the hurdy-gurdy.
  • n. In railroading, a straight piece of track beginning and ending at a curve.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • n. a straight line or plane that touches a curve or curved surface at a point but does not intersect it at that point
  • n. ratio of the opposite to the adjacent side of a right-angled triangle


Latin (līnea) tangēns, tangent-, touching (line), present participle of tangere, to touch.
(American Heritage® Dictionary of the English Language, Fourth Edition)
From Latin tangentem, the accusative of tangēns ("touching") (in the phrase līnea tangēns ("a touching line")), the present participle of the verb tangō ("touch", v), from Proto-Indo-European *tag-, *taǵ- (“to touch”). Cognate with Old English þaccian ("to touch lightly, pat, stroke"). More at thack, thwack. (Wiktionary)



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  • in the communicative sense, of course.

    October 17, 2008