ˌtwenty-ˈtwenty , 20/20 noun [uncountable]
[Date: 1800-1900; Origin: From normal sight being judged on the ability to read letters at a distance of 20 feet]

1. twenty-twenty vision the ability to see things normally, without needing glasses:
A pilot must have twenty-twenty vision.

2. twenty-twenty hindsight used to say that it is easy to know what you should have done in a situation after it has happened, but you did not know what to do earlier

[TahlilGaran] Dictionary of Contemporary English ▲