unsound

adj

1. Not sound

   “unsound mind”

   “In the ensuing financial panic, many persons sustained heavy losses, and large numbers of unsound schemes succumbed.”

   “A striking example comes to mind, in which a scheme to improve the existing buildings finished up as virtually a complete reconstruction, owing to the unsound condition of the original structure!”

   “While he is reasonably effusive about inter-city travel, he is heavily disparaging of all types of stopping service, including those on otherwise busy main lines. His analysis is not entirely unsound, and he tackles some of the questions head on.”

2. (especially)Not sound

   “... A horse labouring under a temporary injury, capable of being speedily cured, is not unsound within the meaning of a warranty of soundness ...”

3. (UK, especially)Not sound

   “You would not like Nietzsche, sir. He is fundamentally unsound.”