Fin field-effect transistor

A fin field-effect transistor (FinFET) is a multigate device, a MOSFET (metal–oxide–semiconductor field-effect transistor) built on a substrate where the gate is placed on two, three, or four sides of the channel or wrapped around the channel (gate all around), forming a double or even multi gate structure. These devices have been given the generic name "FinFETs" because the source/drain region forms fins on the silicon surface.

Source: Wikipedia — Fin field-effect transistor (CC BY-SA 4.0)