The Collaborative International Dictionary of English v.0.48:

Trip \Trip\, v. t.
   1. To cause to stumble, or take a false step; to cause to
      lose the footing, by striking the feet from under; to
      cause to fall; to throw off the balance; to supplant; --
      often followed by up; as, to trip up a man in wrestling.
      [1913 Webster]

            The words of Hobbes's defense trip up the heels of
            his cause.                            --Abp.
                                                  Bramhall.
      [1913 Webster]

   2. (Fig.): To overthrow by depriving of support; to put an
      obstacle in the way of; to obstruct; to cause to fail.
      [1913 Webster]

            To trip the course of law, and blunt the sword.
                                                  --Shak.
      [1913 Webster]

   3. To detect in a misstep; to catch; to convict; also called
      trip up. [R.]
      [1913 Webster]

            These her women can trip me if I err. --Shak.
      [1913 Webster]

   4. (Naut.)
      (a) To raise (an anchor) from the bottom, by its cable or
          buoy rope, so that it hangs free.
      (b) To pull (a yard) into a perpendicular position for
          lowering it.
          [1913 Webster]

   5. (Mach.) To release, let fall, or set free, as a weight or
      compressed spring, as by removing a latch or detent; to
      activate by moving a release mechanism, often
      unintentionally; as, to trip an alarm.
      [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

trip up
    v 1: detect a blunder or misstep; "The reporter tripped up the
         senator" [syn: trip up, catch]
    2: cause to stumble; "The questions on the test tripped him up"
       [syn: trip, trip up]
    3: make an error; "She slipped up and revealed the name" [syn:
       stumble, slip up, trip up]