Cloak

You might be looking for information on the abilities: Cloak, Battle Cloak, or Enhanced Battle Cloak.

Cloaked Federation Galaxy Dreadnought

Cloaking technology is a form of stealth used by races such as Klingon and Romulan for their starships, as well as the Federation in a few of their higher Tier ships. Cloaks also are used by many others for smaller tasks like personal cloaks.

In Star Trek Online cloaks are currently used by the Klingon Empire and Romulan Republic and it features on almost all Klingon vessels (notable exception is the Vo'Quv Carrier and ships from other races like the Gorn, Fek'Ihri, or Orions) and on all Romulan vessels. As of now, the Federation has cloaking ability on only two ships: the Federation Dreadnought Cruiser and Tactical Escort Retrofit. The cloaking device is only usable when the ship is not engaged in combat except for most Birds-of-Prey and all Warbirds, which are capable of using their Battle Cloak to cloak whilst in combat.

In lieu of the Federation having such few ships with the ability to cloak, the Advanced Research Science Vessel and Advanced Research Science Vessel Retrofit do carry the means to detect cloaked ships with Tachyon Detection Field and Tachyon Detection Grid which can utilize the ship, as well as friendly ships in the area, respectively, to enhance this ability.