A holochamber was a holographic device capable of reproducing environments realistically.
In 1525, chief engineer Edrin of the Caeliar constructed a holographic chamber simulating a beach front for the four Earth Starfleet officers housed in Axion to provide them a diversion from their artificial environment. (ST - Destiny novel: Mere Mortals)
In the 2290s, a prototype holochamber was installed aboard the USS Enterprise-B. Captain John Harriman used his holochamber to create the interior of a small Romulan vessel, and abduct Tal Shiar High Examiner Rokan without his knowledge. (ST short story: "Shakedown")