adj. 25B6; adjective OBSERVANT, alert, vigilant, attentive, awake, aware, heedful, sharp-eyed, eagle-eyed; on the lookout, on the qui vive, wary, cautious, careful, chary.
WATCHFUL
Meaning of WATCHFUL in English
Concise Oxford thesaurus English vocabulary. Краткий оксфордский словарь английского языка тезаурус. 2012