Magic resistance

Magic resistance was an innate ability that could prevent magic from taking effect on a creature or person.

In Creatures
Various creatures steeped in magic, like the drow and most dragons and fiends, possessed magic resistance, as did strongly anti-magical ones. The likelyhood to negate any one spell or effect varied widely between different species.

Through Magic
Certain magical items, like a potion of magic resistance or robe of the archmagi, also granted this ability.

The pluma spell also named magic resistance was used to cancel magic in a limited area, but worked technically closer to an anti-magic shell.

The spells lower resistance, pierce magic resistance and pierce any shield on the other hand were designed to improve the chance to overcome creatures' innate resistance against magic.

Background
Magic resistance was a concept used in the 1st and 2nd edition of Dungeons & Dragons. In the 3rd edition it was replaced by the two extraordinary abilities of spell resistance and spell immunity.