1) Alert 2) Attentive 3) Discerning 4) Lawful 5) Observing 6) Open-eyed 7) Watchful 8) Open-eyed 1) Attentive 2) Following religious practices 3) French word used in English 4) Quick to notice 5) Vigilant 
• (n.) An Observantine. • (n.) A sycophantic servant. • (a.) Taking notice; viewing or noticing attentively; watchful; attentive; as, an observant spectator; observant habits. • (a.) Submissively attentive; obediently watchful; regardful; mindful; obedient (to); -- with of, as, to be observant of rules. • (n.) One who obser...
Ob·serv'ant adjective [ Latin observans , -anits , present participle of observare : confer French observant . See Observe .] 1. Taking notice; viewing or noticing attentively; watchful; attentive; as, an observant spectator; observant habits...
[adj] - quick to notice 2. [adj] - paying close attention especially to details
observing adjective quick to notice; showing quick and keen perception
quick to notice; showing quick and keen perception