free from injury, damage, defect, disease, etc.; in good condition; healthy; robust

a sound heart; a sound mind.

financially strong, secure, or reliable

a sound business; sound investments.

competent, sensible, or valid

sound judgment.

having no defect as to truth, justice, wisdom, or reason

sound advice.

of substantial or enduring character

sound moral values.

following in a systematic pattern without any apparent defect in logic

sound reasoning.

uninterrupted and untroubled; deep

sound sleep.

vigorous, thorough, or severe

a sound thrashing.

free from moral defect or weakness; upright, honest, or good; honorable; loyal.

having no legal defect

a sound title to property.

theologically correct or orthodox, as doctrines or a theologian.

deeply; thoroughly

sound asleep.

noun

durability , firmness , integrity , solidity , stability , strength , wholeness , haleness , healthiness , heartiness , lucidity , lucidness , mind , reason , saneness , sense , wit , fastness , hardness , security , stableness , steadiness , sturdiness , sureness , correctness , horse sense , integrality , levelheadedness , solidarity , solvency , truth , weight

adjective

acceptable , effective , valid