The Collaborative International Dictionary of English v.0.48:

Rung \Rung\,
   imp. & p. p. of Ring.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Rung \Rung\, n. [OE. ronge, AS. hrung, a staff, rod, pole; akin
   to G. runge a short, thick piece of iron or wood, OD. ronghe
   a prop, support, Icel. r["o]ng a rib in a ship, Goth. Hrugga
   a staff.]
   1. (Shipbuilding) A floor timber in a ship.
      [1913 Webster]

   2. One of the rounds of a ladder.
      [1913 Webster]

   3. One of the stakes of a cart; a spar; a heavy staff.
      [1913 Webster]

   4. (Mach.) One of the radial handles projecting from the rim
      of a steering wheel; also, one of the pins or trundles of
      a lantern wheel.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Ring \Ring\ (r[i^]ng), v. t. [imp. Rang (r[a^]ng) or Rung
   (r[u^]ng); p. p. Rung; p. pr. & vb. n. Ringing.] [AS.
   hringan; akin to Icel. hringja, Sw. ringa, Dan. ringe, OD.
   ringhen, ringkelen. [root]19.]
   1. To cause to sound, especially by striking, as a metallic
      body; as, to ring a bell.
      [1913 Webster]

   2. To make (a sound), as by ringing a bell; to sound.
      [1913 Webster]

            The shard-borne beetle, with his drowsy hums,
            Hath rung night's yawning peal.       --Shak.
      [1913 Webster]

   3. To repeat often, loudly, or earnestly.
      [1913 Webster]

   To ring a peal, to ring a set of changes on a chime of
      bells.

   To ring the changes upon. See under Change.

   To ring in or To ring out, to usher, attend on, or
      celebrate, by the ringing of bells; as, to ring out the
      old year and ring in the new. --Tennyson.

   To ring the bells backward, to sound the chimes, reversing
      the common order; -- formerly done as a signal of alarm or
      danger. --Sir W. Scott.
      [1913 Webster]

WordNet (r) 3.0 (2006):

rung
    n 1: a crosspiece between the legs of a chair [syn: rung,
         round, stave]
    2: one of the crosspieces that form the steps of a ladder [syn:
       rundle, spoke, rung]

Moby Thesaurus II by Grady Ward, 1.0:

50 Moby Thesaurus words for "rung":
   amount, caliber, compass, cut, degree, doorstep, extent, footrest,
   footstep, grade, height, interval, leap, level, mark, measure,
   notch, nuance, pas, peg, period, pitch, plane, plateau, point,
   proportion, range, ratio, reach, remove, rest, riser, round,
   rundle, scale, scope, shade, shadow, space, spoke, stage, stair,
   standard, stave, step, step stool, stepping-stone, stint, string,
   tread