Definition of "Unsound" :

adjective: of e.g. advice

adjective: physically unsound or diseased

"An unsound limb."

adjective: suffering from severe mental illness

"Of unsound mind."

adjective: not sound financially

"Unsound banking practices."

adjective: not in good condition; damaged or decayed

"An unsound foundation."

adjective: containing or based on a fallacy

"An unsound argument."