Emily Dickinson Lexicon

SA-GA'CIOUS, a. [L. sagax, from sagus, wise, foreseeing; saga, a wise woman; sagio, to perceive readily; Fr. sage, sagesse; Sp. saga, sagaz; It. saggio. The latter signifies wise, prudent, sage, and an essay, which unites this word with seek, and L. sequor.]

1. Quick of scent; as, a sagacious hound; strictly perhaps, following by the scent, which sense is connected with L. sequor; with of; as, sagacious of his quarry. – Milton.
2. Quick of thought; acute in discernment or penetration; as a sagacious head; a sagacious mind. – Locke. I would give more for the criticisms of one sagacious enemy, than for those of a score of admirers. – H. Humphrey