A "secret entrance" refers to a hidden or discreet way to enter a place that is not easily noticeable or known to others. It is typically used to keep something or someone hidden or to enter a location without drawing attention. Full definition
You can also use the drone to locate secret entrances into the facilities, such as sewage pipes, for those of you that prefer stealthy infiltration over the guns blazing approach. (shortpause.com)
Gamers who enjoy a stealth style of gameplay will find several secret entrances and tunnels to explore, new tactical tools equipped and even the ability to capture guard routines or conversations leading to important clues and tips for your mission. (fraghero.com)
Lyon was also known during the German occupation as the «Capital of the Resistance,» and the many narrow passageways, secret entrance ways and above - ground walkways in the Vieux Lyon were perfect for Resistance fighters to escape capture from their occupiers. (theexpeditioner.com)