Polar pattern
How sensitive a microphone is to sound arriving from different angles, drawn as a polar plot.
Omnidirectional mics measure pressure alone and hear equally in every direction. The figure-8, typical of ribbon mics, hears front and back but not the sides. Mix the two and you get the cardioid, which is deaf directly behind — which is why stage mics point away from the wedges. Super- and hypercardioids are tighter at the front but grow a small rear lobe, and the classic mistake is putting the monitor exactly there.
Multi-pattern mics such as the Neumann U 87 put two cardioid capsules back to back and blend them electrically into whatever pattern you ask for. Every directional pattern has a side effect up close: the proximity effect. Crossed figure-8s are also the basis of mid/side stereo.