An incorporeal creature or object has no physical form.
Kind
Creature trait
Also printed in
Player Core 2 p316, Monster Core p362
An incorporeal creature or object has no physical form. It can pass through solid objects, including walls. When inside an object, an incorporeal creature can't perceive, attack, or interact with anything outside the object, and if it starts its turn in an object, it's slowed 1 until the end of its turn. A corporeal and an incorporeal creature can pass through one another, but they can't end their movement in each other's space. An incorporeal creature can't attempt Strength-based checks against physical creatures or objects-only against incorporeal ones-unless those objects have the ghost touch property rune. Likewise, a corporeal creature can't attempt Strength-based checks against incorporeal creatures or objects. Incorporeal creatures usually have immunity to effects or conditions that require a physical body, like disease, poison, and precision damage. They usually have resistance against all damage (except force damage and damage from Strikes with the ghost touch property rune), with double the resistance against non-magical damage.
Creature
Incorporeal is one of 95 creature.
Source: Pathfinder GM Core, p. 330
Bring Incorporeal into a Pathfinder 2e game with The DM Screen.