1) Apt to break 2) Corroded 3) Damaged or decayed 4) Decayed 5) Defective 6) Easily broken 7) Ill-conceived 8) Illogical 9) Not financially strong 10) Not healthy 11) Not in good condition 12) Not sound 13) Not sound financially 14) Not well-founded or valid 15) Prone to injury 16) Rotted 17) Rotten Found on https://www.crosswordclues.com/clue/unsound
not sound; unhealthy, diseased, or disordered, as the body or mind. · decayed or impaired, as timber or foods; defective. · not solid or firm, as foundations. · not well-founded or valid; fallacious: an unsound argument. · easily broken; light: unsound slumber. · not financially strong; unreliable: an unsound corporation. Found on https://www.infoplease.com/dictionary/unsound