What type of bonus is a Monk's AC bonus in Pathfinder, Natural, Deflect, Or some other type? All I know is that it's a Wisdom bonus.
Monks add their Wisdom bonus and an untyped bonus to AC.
The monk in the Core Rulebook says the monk adds their Wisdom bonus to AC/CMD, and also adds an untyped bonus to AC/CMD.
When unarmored and unencumbered, the monk adds his Wisdom bonus (if any) to his AC and his CMD. In addition, a monk gains a +1 bonus to AC and CMD at 4th level. This bonus increases by 1 for every four monk levels thereafter, up to a maximum of +5 at 20th level.
These bonuses to AC apply even against touch attacks or when the monk is flat-footed. He loses these bonuses when he is immobilized or helpless, when he wears any armor, when he carries a shield, or when he carries a medium or heavy load.
It's neither natural armor, nor dodge, nor enhancement, nor deflection, nor luck, or any other typed bonus. The monk's extra bonus AC is untyped.
The unchained monk has essentially the same class feature, with nearly identical wording.