sensible and likely to produce the right results [≠ poor]:
The book is full of sound advice.
a man of great integrity and sound judgement
ecologically/ideologically/theoretically etc sound
environmentally sound farming practices
a sound investment
someone who is sound can be depended on to make good decisions and give good advice
He's very sound on matters of law.
someone who is sound is a good person and can be trusted - used especially by young people:
My mum's sound. She'd never throw me out.
complete and thorough:
thorough[only before noun]
a sound understanding of money and banking systems
a sound knowledge of English
He has sound grasp of European history.
in good condition and not damaged in any way [≠ unsound]:
in good condition
The floor was completely sound.
Is the building structurally sound?
sound as a bell British English spoken (=in perfect condition)
physically or mentally healthy [≠ unsound]
of sound mind law (=not mentally ill)
sound as a bell British English spoken (=in perfect health)
sound sleep is deep and peaceful
sound sleeper (=someone who always sleeps well)
—soundness noun [uncountable]