Princeton's WordNet

1. alert, watchful(adj)

   engaged in or accustomed to close observation

   "caught by a couple of alert cops"; "alert enough to spot the opportunity when it came"; "constantly alert and vigilant, like a sentinel on duty"

2. insomniac, sleepless, watchful(adj)

   experiencing or accompanied by sleeplessness

   "insomniac old people"; "insomniac nights"; "lay sleepless all night"; "twenty watchful, weary, tedious nights"- Shakespeare

Kernerman English Learner's Dictionary

1. watchful(adjective)ˈwɒtʃ fəl

   paying close attention to what is happening

   Neighbors remained watchful after the robberies.

Wiktionary

1. watchful(Adjective)

   observant, vigilant and aware

Webster Dictionary

1. Watchful(adj)

   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

• behoedsaamAfrikaans
• يَقِظ، مُحْتَرِسArabic
• наблюдателенBulgarian
• vigilantePortuguese (BR)
• bdělýCzech
• wachsamGerman
• agtpågivenDanish
• άγρυπνος, προσεκτικόςGreek
• vigilante, atentoSpanish
• tähelepanelikEstonian
• هشيارFarsi
• valpasFinnish
• vigilantFrench
• עֵרָנִיHebrew
• चौकसHindi
• pozoranCroatian
• óvatosHungarian
• waspadaIndonesian
• aðgætinnIcelandic
• vigile, vigilanteItalian
• 用心深いJapanese
• 조심하는Korean
• akylasLithuanian
• modrs; piesardzīgsLatvian
• berjaga-jaga, berhati-hatiMalay
• oplettendDutch
• påpasselig, forsiktigNorwegian
• baczny, czujnyPolish
• vigilantePortuguese
• vigilentRomanian
• внимательный; бдительныйRussian
• bdelý, ostražitýSlovak
• pazljivSlovenian
• oprezanSerbian
• vaksamSwedish
• ซึ่งเฝ้ามองอย่างะมัดระวัง; ซึ่งเฝ้าดูอย่างระมัดระวัง; ซึ่งเฝ้าดูอย่างใกล้ชิดThai
• uyanık, dikkatliTurkish
• 警戒的，留心的Chinese (Trad.)
• пильний; обережнийUkrainian
• ہوشیارUrdu
• thận trọngVietnamese
• 警惕的Chinese (Simp.)