a.
1.
Quick-scented, quick of scent.
2.
Discerning, intelligent, rational, judicious, sage, shrewd, acute, apt, keen, able, perspicacious, wise, sharp-witted, keen-witted, keen-sighted, clear-sighted, long-headed.
3.
Sage, wise, enlightened, gifted, sapient.
4.
Intelligent ( said of animals ).