The Collaborative International Dictionary of English v.0.48:

Intercept \In`ter*cept"\, v. t. [imp. & p. p. Intercepted; p.
   pr. & vb. n. Intercepting.] [L. interceptus, p. p. of
   intercipere to intercept; inter between + capere to take,
   seize: cf. F. intercepter. See Capable.]
   [1913 Webster]
   1. To take or seize by the way, or before arrival at the
      destined place; to cause to stop on the passage; as, to
      intercept a letter; a telegram will intercept him at
      Paris.
      [1913 Webster]

            God will shortly intercept your breath. --Joye.
      [1913 Webster]

   2. To obstruct or interrupt the progress of; to stop; to
      hinder or oppose; as, to intercept the current of a river.
      [1913 Webster]

            Who intercepts me in my expedition?   --Shak.
      [1913 Webster]

            We must meet first, and intercept his course.
                                                  --Dryden.
      [1913 Webster]

   3. To interrupt communication with, or progress toward; to
      cut off, as the destination; to blockade.
      [1913 Webster]

            While storms vindictive intercept the shore. --Pope.
      [1913 Webster]

   4. (Math.) To include between; as, that part of the line
      which is intercepted between the points A and B.

   5. To overhear or view (a communication or message intended
      for another), without hindering its passage; as, to
      intercept a telephone call.
      [PJC]

   6. (Sports) To catch and take possession of (a ball passed
      between members of an opposing team); as, the back
      intercepted the pass and ran the ball back for a
      touchdown.
      [PJC]

   Syn: To cut off; stop; catch; seize; obstruct.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Intercept \In"ter*cept`\, n. (Math.)
   A part cut off or intercepted, as a portion of a line
   included between two points, or cut off two straight lines or
   curves.
   [1913 Webster]

WordNet (r) 3.0 (2006):

intercept
    n 1: the point at which a line intersects a coordinate axis
    v 1: seize on its way; "The fighter plane was ordered to
         intercept an aircraft that had entered the country's
         airspace" [syn: intercept, stop]
    2: tap a telephone or telegraph wire to get information; "The
       FBI was tapping the phone line of the suspected spy"; "Is
       this hotel room bugged?" [syn: wiretap, tap, intercept,
       bug]

Moby Thesaurus II by Grady Ward, 1.0:

69 Moby Thesaurus words for "intercept":
   arrest, attend, attend to, auscultate, be all ears, bend an ear,
   block, bottle up, bug, catch, check, cock the ears, countercheck,
   curb, cut off, dam up, damp, dampen, deflect, delay, detain,
   eavesdrop, examine by ear, give attention, give audience to,
   give ear, grab, hark, head off, hear, hear out, hearken, heed,
   hinder, hold back, hold in check, hold up, impede, inhibit,
   interfere, interfere with, intermeddle, interrupt, intervene,
   keep back, keep in check, lend an ear, listen, listen at,
   listen in, listen to, meddle, oppose, repress, resist, restrain,
   retard, scotch, seize, set back, sit in on, slacken, snub, stop,
   suppress, take, tap, trap, wiretap