Appearing on the same line as the discipline and subdiscipline (when applicable) is a descriptor that further categorizes the power in some way. Some powers have more than one descriptor.
The descriptors that apply to powers are Acid, Cold, Death, Electricity, Evil, Fire, Force, Good, Language-dependent, Light, Mind-affecting, and Sonic.
Most of these descriptors have no game effect by themselves, but they govern how the power interacts with other powers, with spells, with special abilities, with unusual creatures, with alignment, and so on.
A language-dependent power uses intelligible language as a medium.
A mind-affecting power works only against creatures with an Intelligence score of 1 or higher.