The Collaborative International Dictionary of English v.0.48:

Hold \Hold\, v. i.
   In general, to keep one's self in a given position or
   condition; to remain fixed. Hence:
   [1913 Webster]

   1. Not to move; to halt; to stop; -- mostly in the
      imperative.
      [1913 Webster]

            And damned be him that first cries, "Hold, enough!"
                                                  --Shak.
      [1913 Webster]

   2. Not to give way; not to part or become separated; to
      remain unbroken or unsubdued.
      [1913 Webster]

            Our force by land hath nobly held.    --Shak.
      [1913 Webster]

   3. Not to fail or be found wanting; to continue; to last; to
      endure a test or trial; to abide; to persist.
      [1913 Webster]

            While our obedience holds.            --Milton.
      [1913 Webster]

            The rule holds in land as all other commodities.
                                                  --Locke.
      [1913 Webster]

   4. Not to fall away, desert, or prove recreant; to remain
      attached; to cleave; -- often with with, to, or for.
      [1913 Webster]

            He will hold to the one and despise the other.
                                                  --Matt. vi. 24
      [1913 Webster]

   5. To restrain one's self; to refrain.
      [1913 Webster]

            His dauntless heart would fain have held
            From weeping, but his eyes rebelled.  --Dryden.
      [1913 Webster]

   6. To derive right or title; -- generally with of.
      [1913 Webster]

            My crown is absolute, and holds of none. --Dryden.
      [1913 Webster]

            His imagination holds immediately from nature.
                                                  --Hazlitt.
      [1913 Webster]

   Hold on! Hold up! wait; stop; forbear. [Collog] -- To
   hold forth, to speak in public; to harangue; to preach.
      --L'Estrange.

   To hold in, to restrain one's self; as, he wanted to laugh
      and could hardly hold in.

   To hold off, to keep at a distance.

   To hold on, to keep fast hold; to continue; to go on. "The
      trade held on for many years," --Swift.

   To hold out, to last; to endure; to continue; to maintain
      one's self; not to yield or give way.

   To hold over, to remain in office, possession, etc., beyond
      a certain date.

   To hold to or To hold with, to take sides with, as a
      person or opinion.

   To hold together, to be joined; not to separate; to remain
      in union. --Dryden. --Locke.

   To hold up.
      (a) To support one's self; to remain unbent or unbroken;
          as, to hold up under misfortunes.
      (b) To cease raining; to cease to stop; as, it holds up.
          --Hudibras.
      (c) To keep up; not to fall behind; not to lose ground.
          --Collier.
          [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

178 Moby Thesaurus words for "hold on":
   abide, adhere, adhere to, agglomerate, aim, aim at, await,
   be caught short, be short, bear up, belong, bend, bide,
   bide the issue, bite, bucket, bucketshop, bunch, carry on,
   cease not, clasp, cleave, cleave to, clench, clinch, cling,
   cling to, clip, clot, cluster, clutch, coagulate, cohere,
   come up fighting, congeal, conglomerate, continue, continue to be,
   dally, dawdle, defeat time, defy time, delay, deposit margin,
   determine, dillydally, direct, directionize, drag on, dwell,
   embrace, endure, exist, extend, fix, fix on, freeze to, go along,
   go long, go on, grapple, grasp, grip, gripe, grow together,
   hang about, hang around, hang in, hang in there, hang on,
   hang on to, hang together, hang tough, hold, hold everything,
   hold fast, hold on to, hold out, hold steady, hold tight,
   hold together, hold up, hold your horses, hug, jog on, keep,
   keep going, keep hold of, keep on, last, last long, last out,
   level at, linger, live, live on, live through, live through it,
   live with it, loiter, maintain, make a killing, make a scoop,
   margin up, mark time, mass, miss the market, never cease,
   never let go, never say die, nip, not give up, operate,
   overstay the market, perdure, perennate, persist, play the market,
   plunge, point, point at, point to, present, prevail, pyramid,
   remain, run, run on, scalp, scoop the market, set, sight on,
   sit tight, sit up, slog on, solidify, speculate, stag,
   stag the market, stagger on, stand, stand up, stay, stay it out,
   stay on, stay put, stay the distance, stay up, stay with it, stick,
   stick around, stick it, stick it out, stick out, stick to,
   stick to it, stick together, stick with it, subsist, survive,
   sustain, take a flier, take hold of, take time, tarry, tide over,
   tough it out, trade on margin, train, train upon, turn, turn upon,
   venture, wait, wait a minute, wait and see, wear, wear well