(a.) Full of watch; vigilant; attentive; careful to observe closely; observant; cautious; -- with of before the thing to be regulated or guarded; as, to be watchful of one's behavior; and with against before the thing to be avoided; as, to be watchful against the growth of vicious habits.

Argus-eyed advertent agog alert all ears all eyes assiduous attentive aux aguets aware careful cautious chary circumspect concentrated conscious covering custodial defensive diligent eagle-eyed earnest finical finicking finicky fostering guarded guardian guarding hawk-eyed heedful immunizing intense intent intentive keen-eyed lidless meticulous mindful nice niggling observant observing on guard on the ball on the job on the lookout on the watch open-eared open-eyed openmouthed parental preventive prompt prophylactic protecting protective prudent quick ready regardful safeguarding screening sharp-eyed sheltering shielding sleepless tutelary unsleeping vigilant wakeful wary wide-awake with open eyes