Definition of sound adjective from the Oxford Advanced Learner's Dictionary

     

    sound

     adjective
    adjective
    BrE BrE//saʊnd//
     
    ; NAmE NAmE//saʊnd//
     
    (sounder, soundest)
     
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    reliable
  1. 1sensible; that you can rely on and that will probably give good results a person of sound judgement He gave me some very sound advice. This gives the design team a sound basis for their work. The proposal makes sound commercial sense. Their policies are environmentally sound. opposite unsound
  2. thorough
  3. 2[only before noun] good and thorough a sound knowledge/understanding of something He has a sound grasp of the issues.
  4. not damaged/hurt
  5. 3in good condition; not damaged, hurt, etc. We arrived home safe and sound. to be of sound mind (= not mentally ill) The house needs attention but the roof is sound. opposite unsound
  6. sleep
  7. 4[usually before noun] deep and peaceful to have a sound night’s sleep to be a sound sleeper
  8. good, but not excellent
  9. 5good and accurate, but not excellent a sound piece of writing a sound tennis player
  10. physical punishment
  11. 6severe to give somebody a sound beating
  12. Word Originadjective Middle English : from Old English gesund, of West Germanic origin; related to Dutch gezond and German gesund.Extra examples It was a financially sound investment. She had a perfectly sound reason for acting as she did. That seems like fairly sound advice. The roof is in reasonably sound condition. We arrived home safe and sound. Do you think the evidence is sound? He’s a person of very sound judgement. My father once gave me some very sound advice. This was another sound performance by the team. You need to have sound reasons to back up your arguments.Idioms (informal) in perfect condition The doctor said I was as sound as a bell. More Like ThisSimiles in idioms (as) bald as a coot, (as) blind as a bat, (as) bright as a button, (as) bold as brass, as busy as a bee, as clean as a whistle, (as) dead as a/​the dodo, (as) deaf as a post, (as) dull as ditchwater, (as) fit as a fiddle, as flat as a pancake, (as) good as gold, (as) mad as a hatter/​a March hare, (as) miserable/​ugly as sin, as old as the hills, (as) pleased as Punch, as pretty as a picture, (as) regular as clockwork, (as) quick as a flash, (as) safe as houses, (as) sound as a bell, (as) steady as a rock, (as) thick as two short planks, (as) tough as old bootsSee worksheet.
See the Oxford Advanced American Dictionary entry: sound