Polymorphed

Polymorphed is a status effect that induces a polymorph change to the target creature - transforming their physical being into a different creature. This is viewed as a negative status effect, because it is imposed upon the creature against their will by the originator of the polymorph power, ability or hostile spell effect.
The transformation is instant and permanent until a Dispel Magic is cast successfully upon the affected creature. The natural attacks of the new form also become available and all clothes and equipment that the target was wearing will mold into the new form.
A character who possesses shapeshifting abilities as innate ability (e.g. Slayer Form for main character) can also use those to escape from a Polymorph spell. Even when turning back immediately, the hostile polymorph will have been cancelled, regardless of duration.
The polymorphed status effect is triggered by a spell cast at the target (or it could be an innate ability - but it is still launched at the target). A saving throw is normally allowed to negate the transformation, and typically the polymorph effect can be blocked by magic resistance. The polymorph other spell can also be protected against by any spell protection that targets level 4 spells (Globe of Invulnerability, Shield of the Archons...), or by Improved Invisibility.