[1] : The Collaborative International Dictionary of English v.0.48

watchful \watch"ful\, 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.
   "many a watchful night." --shak. "happy watchful shepherds."
   --milton.
   1913 webster

         'twixt prayer and watchful love his heart dividing.
                                                  --keble.
   1913 webster

   syn: vigilant; attentive; cautious; observant; circumspect;
        wakeful; heedful.
        1913 webster -- watch"fully, adv. --
        watch"fulness, n.
        1913 webster
see also:
watch"fully watch"fulness 

[2] : WordNet (r) 2.0

watchful
     adj 1: carefully observant or attentive; on the lookout for
            possible danger; "a policy of open-eyed awareness";
            "the vigilant eye of the town watch"; "there was a
            watchful dignity in the room"; "a watchful parent with
            a toddler in tow" syn: argus-eyed, open-eyed, vigilant,
             wakeful
     2: experiencing or accompanied by sleeplessness; "insomniac old
        people"; "insomniac nights"; "lay sleepless all night";
        "twenty watchful, weary, tedious nights"- shakespeare
        syn: insomniac, sleepless
see also:
argus-eyed open-eyed vigilant wakeful insomniac sleepless 

[3] : Moby Thesaurus II by Grady Ward, 1.0

74 moby thesaurus words for "watchful":
   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

Watchful >> W Words
Watchful, definition of term: Watchful
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