sagaciousEnglishOxford New American Dictionarysagacious /səˈɡāSHəs, səˈɡeɪʃəs / ▸ adjective having or showing keen mental discernment and good judgment; shrewd: they were sagacious enough to avoid any outright confrontation. – DERIVATIVES sagaciously /səˈɡāSHəslē, səˈɡeɪʃəsli / adverb– ORIGIN early 17th century : from Latin sagax, sagac- ‘wise’ + -ious.