Shapeshifter
From Memory Alpha, the free Star Trek reference.
Shapeshifter is a generic and overly generalized term applied to species which are capable of altering their physical form. The degree of physical transformation varies between different species. Some, such as the Chameloids and the Allasomorphs of Daled IV, are only able to change between humanoid forms. Others, such as the Changelings from the Gamma Quadrant, are capable of mimicking virtually any phase of matter, including fog and fire, down to the molecular level. Odo is an example of this type of Changeling.
It is most likely that Changelings are themselves warp-capable as Laas pursued a Runabout which just dropped out of warp speed, this makes Laas at least as fast as an impulse drive Spacecraft but suggests warp-capablity. (DS9: "Chimera")
