observant

Synonyms: advertent alive attentive bright clear-sighted comprehending considering contemplating correct deducing detecting discerning discovering discriminating eager eagle-eyed heedful intelligent intentive interested keen mindful not missing a trick obedient observative on one’s toes on the ball penetrating perceptive questioning quick regardful searching sensitive sharp sharp-eyed surveying understanding vigilant wide-awake

Antonyms: careless inattentive indifferent thoughtless unaware unmindful unobservant unwatchful