" unsound "

1: temporarily suffering from a disorder of the body;

  * e.g., " ... an unsound horse that will have to be disqualified from the race "

•  Synonyms : 

•  ailing,

•  bad,

•  down,

•  ill,

•  indisposed,

•  peaked,

•  peaky,

•  poorly,

•  punk,

•  run-down,

•  sick,

•  sickened,

•  unhealthy,

•  unwell

•  Antonyms : 

•  hale,

•  healthful,

•  healthy,

•  sound,

•  well,

•  whole,

•  wholesome

2: not using or following good reasoning;

  * e.g., " ... it is clearly unsound to argue that just because a scientific explanation for that phenomenon does not currently exist, no such explanation is possible "

•  Synonyms : 

•  fallacious,

•  illegitimate,

•  illogical,

•  inconsequent,

•  inconsequential,

•  invalid,

•  irrational,

•  nonrational,

•  unreasonable,

•  unreasoning,

•  weak

•  Antonyms : 

•  logical,

•  rational,

•  reasonable,

•  sound,

•  valid,

•  well-founded,

•  well-grounded

3: unable to think in a clear or sensible way;

  * e.g., " ... disgruntled relatives tried to prove that the woman was of unsound mind when she made her will "

•  Synonyms : 

•  bats,

•  batty,

•  bonkers,

•  brainsick,

•  certifiable,

•  cracked,

•  crackers,

•  crazed,

•  crazy,

•  daft,

•  demented,

•  deranged,

•  haywire,

•  insane,

•  loco,

•  mad,

•  maniacal,

•  mental,

•  non compos mentis,

•  nuts,

•  nutty,

•  psycho,

•  psychotic,

•  unbalanced,

•  unhinged,

•  wud

•  Antonyms : 

•  balanced,

•  compos mentis,

•  sane,

•  sound,

•  uncrazy