Definition of twenty-twenty in English:

twenty-twenty

(also 20/20)

adjective

  • Denoting vision of normal sharpness.

    ‘someone with previously perfect 20-20 vision may first notice this change around the age of 45’
    • ‘I guess my twenty-twenty eyesight went out with the lights.’
    • ‘It didn't take twenty-twenty vision to see the worry cross her features.’
    • ‘‘I took you to the optometrist and she said that you had perfect twenty-twenty vision… I don't understand machines these days… ‘she mumbled to herself and walked back out.’’
    • ‘For example we could make sure they had something as simple as twenty-twenty vision, or something as complicated as great strength.’
    • ‘They slowly faded into the lenses, leaving only crystalline images, better than twenty-twenty vision.’

Origin

Late 19th century: the Snellen fraction for normal visual acuity (see Snellen test).