adjective.
On the alert, as for danger or error; watchful. synonym: careful.
The Century Dictionary and Cyclopedia
Watchful, as one who watches during the hours for sleep; ever awake and on the alert; attentive to discover and avoid danger, or to provide for safety; circumspect; cautious; wary.
Indicating vigilance.
Synonyms 1. Wakeful, etc. See watchful.
the GNU version of the Collaborative International Dictionary of English
adjective.
Attentive to discover and avoid danger, or to provide for safety; wakeful; watchful; circumspect; wary.
adjective.Watchful, especially for danger or disorder; alert; wary
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adjective.
carefully observant or attentive; on the lookout for possible danger
Word Usage
""The focus for Thursday is on the ECB meeting and whether or not Trichet uses the code word 'vigilant,'" wrote analysts at BNP Paribas SA including Ray Attrill, a senior currency strategist in New York in a note yesterday."