perspicacious
pur-spih-KAY-shusadjMeaning quick to notice and understand things; sharp-minded
Memory hook PURR-SPY-CAT: she sees through it all. The Purr-Spy Cat spots the mouse hiding by the boot that everyone else walked right past. A sharp noticer like her is perspicacious.
The perspicacious detective noticed that the muddy boots were two sizes too small.
In context Most readers missed the clue on page ten, but the perspicacious few who caught it guessed the ending long before the last chapter.
Similar perceptive, sharp, shrewd, insightful
Opposite obtuse, dull, slow-witted
From Latin perspicax, “sharp-sighted,” from perspicere, “to look through”: per (through) + specere (to look).