ounce S3 /aʊns/ BrE AmE noun [countable] ( written abbreviation oz )
[ Date: 1300-1400 ; Language: Old French ; Origin: unce , from Latin uncia 'twelfth part, ounce' ]
1 . a unit for measuring weight, equal to 28.35 grams. There are 16 ounces in a pound. ⇨ ↑ fluid ounce
2 . an ounce of sense/truth/decency etc any sense, truth etc at all:
If you had an ounce of sense you wouldn’t believe him!
3 . every (last) ounce of courage/energy/strength etc all the courage, energy etc that you have:
Every ounce of attention was focused on our common goal.
4 . an ounce of prevention (is worth a pound of cure) used to say that it is better to prevent a problem before it happens than to try to solve it after it has happened
5 . not an ounce of fat (on somebody) if there is not an ounce of fat on someone, they are thin and usually look healthy