acuity in WordNet English dictionary

1. a quick and penetrating intelligence
   "he argued with great acuteness"; "I admired the keenness of his mind"
   acuteness  acuity  sharpness  keenness 
   
2. sharpness of vision; the visual ability to resolve fine detail (usually measured by a Snellen chart)
   acuity  visual acuity  sharp-sightedness