acuity

n [U] (fml 文) (esp of thought or the senses) sharpness; acuteness （尤指思想或感官）敏锐, 尖锐.

action painting, action replay, action stations, actionable, activate, activation, active, active service (US also active duty), actively, activeness, activist, activity, actor, actress, actual, actuality, actually, actuarial, actuary, actuate, acumen, acupuncture, acupuncturist, acute, acute angle, acute mark, acutely, acuteness, AD, ad hoc, ad infinitum, ad lib, ad nauseam, ad-lib, adage, adagio, Adam, Adam's apple, adamant, adamantly,