Shapeshifting, a common representation in fiction, mythology and several fantasy-related games.

In elementary algebra, a polymorph is an integer which can be expressed in multiple ways using a certain form (further explanation at mathworld.wolfram.com).

Dreissena polymorpha, the scientific name for the Zebra mussel.

Polymorphism (materials science), a solid which shares chemical composition with another material but is composed of a different crystal lattice or form, often called a polymorph.

Polymorph (Red Dwarf episode) is an episode of the British sci-fi sitcom Red Dwarf.

Polycaprolactone, often called a polymorph in polymer science.

Polymorph (novel), a 1997 novel by Scott Westerfeld.