Ability Score Loss

Some attacks deal damage to an ability score in the form of
ability damage or ability drain. Ability damage must be healed
naturally or magically, and ability drain must be restored
by magic.
A few effects impose an effective ability score reduction,
which is different from ability score loss. Any such reduction
disappears at the end of the effect’s duration, and the ability
score immediately returns to its former value.
The capacity that some creatures have to damage or drain
ability scores is a supernatural one, requiring some sort of
attack. Such creatures don’t damage or drain passively, such
as when enemies strike them, even if an enemy attacks using
unarmed attacks or natural weapons.