1. （视力、听力、思维的）敏锐，敏锐度
Acuity is sharpness of vision or hearing, or quickness of thought.

1. a quick and penetrating intelligence

e.g. he argued with great acuteness
I admired the keenness of his mind

Synonym: acutenesssharpnesskeenness

2. sharpness of vision
the visual ability to resolve fine detail (usually measured by a Snellen chart)

Synonym: visual acuitysharp-sightedness