The Collaborative International Dictionary of English v.0.48:

Suicidal \Su"i*ci`dal\, a.
   Partaking of, or of the nature of, the crime or suicide. --
   Su"i*ci`dal*ly, adv.
   [1913 Webster]

WordNet (r) 3.0 (2006):

suicidal
    adj 1: dangerous to yourself or your interests; "suicidal
           impulses"; "a suicidal corporate takeover strategy"; "a
           kamikaze pilot" [syn: self-destructive, suicidal]

Moby Thesaurus II by Grady Ward, 1.0:

92 Moby Thesaurus words for "suicidal":
   baneful, bloodthirsty, bloody, bloody-minded, bowed-down,
   calamitous, cast down, cataclysmal, cataclysmic, catastrophic,
   consuming, consumptive, cruel, crushed, cut up, cutthroat, dashed,
   deadly, deep-troubled, dejected, demolishing, demolitionary,
   depredatory, depressed, desolate, desolating, despairing,
   despondent, desponding, destroying, destructive, devastating,
   disastrous, disconsolate, discouraged, disheartened, dispirited,
   doomful, down, downcast, downhearted, drooping, droopy, fatal,
   fateful, feeling low, fratricidal, gory, heart-stricken,
   heart-struck, heartless, heartsick, homicidal, hypochondriac,
   hypochondriacal, in low spirits, in the depths, in the doldrums,
   in the dumps, internecine, languishing, low, low-spirited,
   miserable, murderous, nihilist, nihilistic, pessimistic, pining,
   ravaging, red-handed, ruining, ruinous, sanguinary,
   self-destructive, slaughterous, spiritless, stricken, subdued,
   subversionary, subversive, vandalic, vandalish, vandalistic,
   wasteful, wasting, weary of life, withering, woebegone, woeful,
   world-weary, wretched