The Collaborative International Dictionary of English v.0.48:

Destructive \De*struc"tive\, a. [L. destructivus: cf. F.
   destructif.]
   Causing destruction; tending to bring about ruin, death, or
   devastation; ruinous; fatal; productive of serious evil;
   mischievous; pernicious; -- often with of or to; as,
   intemperance is destructive of health; evil examples are
   destructive to the morals of youth.
   [1913 Webster]

         Time's destructive power.                --Wordsworth.
   [1913 Webster]

   Destructive distillation. See Distillation.

   Destructive sorties(Logic), a process of reasoning which
      involves the denial of the first of a series of dependent
      propositions as a consequence of the denial of the last; a
      species of reductio ad absurdum. --Whately.

   Syn: Mortal; deadly; poisonous; fatal; ruinous; malignant;
        baleful; pernicious; mischievous.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Destructive \De*struc"tive\, n.
   One who destroys; a radical reformer; a destructionist.
   [1913 Webster]

WordNet (r) 3.0 (2006):

destructive
    adj 1: causing destruction or much damage; "a policy that is
           destructive to the economy"; "destructive criticism"
           [ant: constructive]

Moby Thesaurus II by Grady Ward, 1.0:

101 Moby Thesaurus words for "destructive":
   adverse, annihilative, antithetical, bad, baleful, baneful, black,
   brutal, calamitous, cataclysmal, cataclysmic, catastrophic,
   catching, communicable, condemnatory, conflicting, consuming,
   consumptive, contagious, contradictory, contrary, critical,
   damaging, dangerous, deadly, death-bringing, deathful, deathly,
   deleterious, demolishing, demolitionary, depredatory, derogatory,
   desolating, destroying, detrimental, devastating, dire,
   disapproving, disastrous, disparaging, doomful, envenomed, fatal,
   fateful, fell, feral, fratricidal, grievous, harmful, hurtful,
   infectious, infective, injurious, internecine, killing, lethal,
   malign, malignant, mephitic, miasmal, miasmatic, miasmic, mortal,
   negative, nihilist, nihilistic, noxious, opposed, opposing,
   pernicious, pestiferous, pestilential, poisonous, ravaging,
   ruining, ruinous, savage, self-destructive, shattering,
   subversionary, subversive, suicidal, toxic, toxicant, toxiferous,
   tragic, unfavorable, unwholesome, vandalic, vandalish, vandalistic,
   venenate, veneniferous, venenous, venomous, virulent, wasteful,
   wasting, withering, wreckful