1. (noun)watchfulness, wakefulness, vigilance, alertness the process of paying close and continuous attention "wakefulness, watchfulness, and bellicosity make a good hunter"; "vigilance is especially susceptible to fatigue"
2. (noun)alertness, alerting a state of readiness to respond "alerting was indicated by the desynchronization of the EEG"
3. (noun)alertness, sharp-sightedness, on the qui vive lively attentiveness
Definition of 'alertness' 
