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