covert is in secret, so overt would be out in the open...
For example in Surveillance:
Covert surveillance is any hidden equipment or personnel used to watch, observe, or otherwise record people, objects, data, events, or facts. This is in an effort to compile the raw material used to produce intelligence.
Overt surveillance is when the subject has been informed of the nature and scope of the surveillance being conducted and/or the surveillance devices are clearly labeled and displayed. Obvious