ounce
noun /aʊns/
  /aʊns/
 Idioms - [countable] (abbreviation oz)(in Britain and North America) a unit for measuring weight, 116 of a pound, equal to 28.35 grams see also fluid ounceTopics Cooking and eatingc1, Maths and measurementc1
 - [singular] ounce of something (informal) (used especially with negatives) a very small quantity of something
- There's not an ounce of truth in her story.
 
 
Word OriginMiddle English: from Old French unce, from Latin uncia ‘twelfth part (of a pound or foot)’; compare with inch.
Idioms 
an ounce of prevention is better than a pound of cure (US English) 
(British English prevention is better than cure)
- (saying) it is better to stop something bad from happening rather than try to deal with the problems after it has happened