资料来源 : Webster's Revised Unabridged Dictionary (1913)

Sine \Sine\, n. [LL. sinus a sine, L. sinus bosom, used in
   translating the Ar. jaib, properly, bosom, but probably read
   by mistake (the consonants being the same) for an original
   j[=i]ba sine, from Skr. j[=i]va bowstring, chord of an arc,
   sine.] (Trig.)
      (a) The length of a perpendicular drawn from one extremity
          of an arc of a circle to the diameter drawn through
          the other extremity.
      (b) The perpendicular itself. See {Sine of angle}, below.

   {Artificial sines}, logarithms of the natural sines, or
      logarithmic sines.

   {Curve of sines}. See {Sinusoid}.

   {Natural sines}, the decimals expressing the values of the
      sines, the radius being unity.

   {Sine of an angle}, in a circle whose radius is unity, the
      sine of the arc that measures the angle; in a right-angled
      triangle, the side opposite the given angle divided by the
      hypotenuse. See {Trigonometrical function}, under
      {Function}.

   {Versed sine}, that part of the diameter between the sine and
      the arc.