A transmorphic cloaking device was a type of advanced cloaking device introduced by the Romulans by the year 2400 in the War of the Prophets timeline.

The Altanex was equipped with transmorphic cloaking devices. Nog noted that meant the ship did not require the use of shields but that also the Romulans were using Grigari biogenic components. (DS9 - Millennium novel: The War of the Prophets)