[1] : The Collaborative International Dictionary of English v.0.48

ballast \bal"last\ ba^l"last, n. d. ballast; akin to dan.
   baglast, ballast, osw. barlast, sw. ballast. the first part
   is perh. the same word as e. bare, adj.; the second is last a
   burden, and hence the meaning a bare, or mere, load. see
   bare, a., and last load.
   1. naut. any heavy substance, as stone, iron, etc., put
      into the hold to sink a vessel in the water to such a
      depth as to prevent capsizing.
      1913 webster

   2. any heavy matter put into the car of a balloon to give it
      steadiness.
      1913 webster

   3. gravel, broken stone, etc., laid in the bed of a railroad
      to make it firm and solid.
      1913 webster

   4. the larger solids, as broken stone or gravel, used in
      making concrete.
      1913 webster

   5. fig.: that which gives, or helps to maintain, uprightness,
      steadiness, and security.
      1913 webster

            it piety is the right ballast of prosperity.
                                                  --barrow.
      1913 webster

   ballast engine, a steam engine used in excavating and for
      digging and raising stones and gravel for ballast.

   ship in ballast, a ship carrying only ballast.
      1913 webster
see also:
bare last ballast engine ship in ballast 

[2] : The Collaborative International Dictionary of English v.0.48

ballast \bal"last\, v. t. imp.  p. p. ballasted; p. pr. 
   vb. n. ballasting.
   1. to steady, as a vessel, by putting heavy substances in the
      hold.
      1913 webster

   2. to fill in, as the bed of a railroad, with gravel, stone,
      etc., in order to make it firm and solid.
      1913 webster

   3. to keep steady; to steady, morally.
      1913 webster

            't is charity must ballast the heart. --hammond.
      1913 webster
see also:
ballasted ballasting 

[3] : WordNet (r) 2.0

ballast
     n 1: any heavy material used to stabilize a ship or airship
     2: coarse gravel laid to form a bed for streets and railroads
     3: an attribute that tends to give stability in character and
        morals; something that steadies the mind or feelings
     4: a resistor inserted into a circuit to compensate for changes
        as those arising from temperature fluctuations syn: ballast
        resistor, barretter
     5: an electrical device for starting and regulating fluorescent
        and discharge lamps syn: light ballast
     v : make steady with a ballast
see also:
ballast resistor barretter light ballast 

[4] : Moby Thesaurus II by Grady Ward, 1.0

44 moby thesaurus words for "ballast":
   balance, break bulk, break out ballast, clear for action,
   clear the decks, consideration, counterbalance, counterpoise,
   counterweight, equipoise, equivalent, firm, firm up, freeze,
   give-and-take, hold, immobilize, keep, lead, makeweight, nail down,
   offset, pin down, poise, quid pro quo, retain, sandbag, setoff,
   shift ballast, shoot ballast, something of value, stabilitate,
   stabilize, steady, stick, tit for tat, transfix, trim, trim ship,
   trim up, weigh down, weight, weight down, wing out ballast

Ballast >> B Words
Ballast, definition of term: Ballast
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