This simply means the way the microphone picks up the sound source. Microphones can pickup sound from all around, or a specific direction or area.
Defines a microphone?s response to sounds arriving from various directions or angles. The cardioid microphone, for example has a heart shaped pickup pattern.
The microphones ability to pickup sound depending on the location of that sound relative to the microphone. Also see bi-directional, omnidirectional, unidirectional.