The Collaborative International Dictionary of English v.0.48:
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[imac]ba sine, from Skr. j[imac]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
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
Versed sine, that part of the diameter between the sine and