1. keenness Sharpness, acuteness, and insight, however keen, and penetration, however deep, fall short of the meaning of acumen, which implies also ability to use these qualities to advantage. There ar Synonyms: acumen, acuteness, insight, perspicacity, sharpness, cleverness, keenness, sagacity, shrewdness, discernment, penetration Antonyms: bluntness, dulness, obtuseness, stupidity