Segment \Seg"ment\, n. [L. segmentum, fr. secare to cut, cut
   off: cf. F. segment. See Saw a cutting instrument.]
   1. One of the parts into which any body naturally separates
      or is divided; a part divided or cut off; a section; a
      portion; as, a segment of an orange; a segment of a
      compound or divided leaf.
      [1913 Webster]

   2. (Geom.) A part cut off from a figure by a line or plane;
      especially, that part of a circle contained between a
      chord and an arc of that circle, or so much of the circle
      as is cut off by the chord; as, the segment acb in the
      Illustration.
      [1913 Webster]

   3. (Mach.)
      (a) A piece in the form of the sector of a circle, or part
          of a ring; as, the segment of a sectional fly wheel or
          flywheel rim.
      (b) A segment gear.
          [1913 Webster]

   4. (Biol.)
      (a) One of the cells or division formed by segmentation,
          as in egg cleavage or in fissiparous cell formation.
      (b) One of the divisions, rings, or joints into which many
          animal bodies are divided; a somite; a metamere; a
          somatome.
          [1913 Webster]

   Segment gear, a piece for receiving or communicating
      reciprocating motion from or to a cogwheel, consisting of
      a sector of a circular gear, or ring, having cogs on the
      periphery, or face.

   Segment of a line, the part of a line contained between two
      points on it.

   Segment of a sphere, the part of a sphere cut off by a
      plane, or included between two parallel planes.

   Ventral segment. (Acoustics) See Loor, n., 5.
      [1913 Webster]

Loop \Loop\, n. [Cf. Ir. & Gael. lub loop, noose, fold, thong,
   bend, lub to bend, incline.]
   1. A fold or doubling of a thread, cord, rope, etc., through
      which another thread, cord, etc., can be passed, or which
      a hook can be hooked into; an eye, as of metal; a staple;
      a noose; a bight.
      [1913 Webster]

            That the probation bear no hinge, nor loop
            To hang a doubt on.                   --Shak.
      [1913 Webster]

   2. A small, narrow opening; a loophole.
      [1913 Webster]

            And stop all sight-holes, every loop from whence
            The eye of Reason may pry in upon us. --Shak.
      [1913 Webster]

   3. A curve of any kind in the form of a loop.
      [1913 Webster]

   4. (Telegraphy) A wire forming part of a main circuit and
      returning to the point from which it starts.
      [1913 Webster]

   5. (Acoustics) The portion of a vibrating string, air column,
      etc., between two nodes; -- called also ventral segment.
      [1913 Webster]

   Loop knot, a single knot tied in a doubled cord, etc. so as
      to leave a loop beyond the knot. See Illust. of Knot.
      [1913 Webster]

Ventral \Ven"tral\, a. [L. ventralis, fr. venter the belly;
   perhaps akin to G. wanst: cf. F. ventral.]
   1. (Anat.) Of, pertaining to, or situated near, the belly, or
      ventral side, of an animal or of one of its parts; hemal;
      abdominal; as, the ventral fin of a fish; the ventral root
      of a spinal nerve; -- opposed to dorsal.
      [1913 Webster]

   2. (Bot.)
      (a) Of or pertaining to that surface of a carpel, petal,
          etc., which faces toward the center of a flower.
      (b) Of or pertaining to the lower side or surface of a
          creeping moss or other low flowerless plant. Opposed
          to dorsal.
          [1913 Webster]

   Ventral fins (Zool.), the posterior pair of fins of a fish.
      They are often situated beneath the belly, but sometimes
      beneath the throat.

   Ventral segment. (Acoustics) See Loop, n., 5.
      [1913 Webster]