Answer: unsound

AnswerCrossword Clue
UNSOUNDFaulty, as a plan
unsoundInjured, ill, or diseased, esp. (of a horse) lame
unsoundnot sound
unsoundNot safe or robust; in poor condition
unsoundNot based on sound evidence or reasoning and therefore unreliable or unacceptable
unsound(of a person) Not competent, reliable, or holding acceptable views
UNSOUNDIll-conceived
UNSOUNDProne to injury
UNSOUNDIllogical
UNSOUNDNot healthy
UNSOUNDFallacious, as an argument
UNSOUNDNot good, as ideas go
UNSOUNDDefective
UNSOUNDShaky
UNSOUNDInsecure.
UNSOUNDSpecious.
UNSOUNDFallacious
UNSOUNDApt to break
UNSOUNDLikely to fail
UNSOUNDNot firm, as a foundation