PERSPICACIOUS
perspicacious, clear-sighted, clear-eyed
(adjective) mentally acute or penetratingly discerning; “too clear-eyed not to see what problems would follow”; “chaos could be prevented only by clear-sighted leadership”; “much too perspicacious to be taken in by so spurious an argument”
perspicacious, sagacious, sapient
(adjective) acutely insightful and wise; “much too perspicacious to be taken in by such a spurious argument”; “observant and thoughtful, he was given to asking sagacious questions”; “a source of valuable insights and sapient advice to educators”
Source: WordNet® 3.1
Etymology
Adjective
perspicacious (comparative more perspicacious, superlative most perspicacious)
(figuratively) Of acute discernment; having keen insight; mentally perceptive.
(obsolete) Able to physically see clearly; quick-sighted; sharp-sighted.
Source: Wiktionary
Per`spi*ca"cious, a. Etym: [L. perspicax, -acis, fr. perspicere to
look through: cf. F. perspicace. See Perspective.]
1. Having the power of seeing clearly; quick-sighted; sharp of sight.
2. Fig.: Of acute discernment; keen.
– Per`spi*ca"cious*ly, adv.
– Per`spi*ca"cious*ness, n.
Source: Webster’s Unabridged Dictionary 1913 Edition