The Collaborative International Dictionary of English v.0.48:

Leverage \Lev"er*age\ (l[e^]v"[~e]r*[asl]j or
   l[=e]"v[~e]r*[asl]j), n.
   The action of a lever; mechanical advantage gained by the
   lever.
   [1913 Webster]

   Leverage of a couple (Mech.), the perpendicular distance
      between the lines of action of two forces which act in
      parallel and opposite directions.

   Leverage of a force, the perpendicular distance from the
      line in which a force acts upon a body to a point about
      which the body may be supposed to turn.
      [1913 Webster]

WordNet (r) 3.0 (2006):

leverage
    n 1: the mechanical advantage gained by being in a position to
         use a lever [syn: leverage, purchase]
    2: strategic advantage; power to act effectively; "relatively
       small groups can sometimes exert immense political leverage"
    3: investing with borrowed money as a way to amplify potential
       gains (at the risk of greater losses) [syn: leverage,
       leveraging]
    v 1: supplement with leverage; "leverage the money that is
         already available"
    2: provide with leverage; "We need to leverage this company"

Moby Thesaurus II by Grady Ward, 1.0:

63 Moby Thesaurus words for "leverage":
   aeromechanics, animal mechanics, ascendancy, authority,
   biomechanics, celestial mechanics, charisma, charm, clout,
   consequence, control, credit, dominance, domination, effect,
   electromechanics, eminence, enchantment, esteem, favor,
   fluid mechanics, force, good feeling, hold, hydromechanics,
   importance, incidental power, influence, influentiality,
   insinuation, leadership, magnetism, mastery, mechanical arts,
   mechanics, moment, personality, persuasion, potency, power,
   predominance, preponderance, pressure, prestige, purchase,
   quantum mechanics, rational mechanics, reign, repute, rule, say,
   servomechanics, statistical mechanics, suasion, subtle influence,
   suggestion, supremacy, sway, upper hand, wave mechanics, weight,
   whip hand, zoomechanics