The electron dislodged during Compton scattering is referred to as:

In the context of Compton scattering, the incident photon interacts with a loosely bound or free electron in an atom, transferring some of its energy to that electron. As a result, the electron is ejected from its atom, which is why it is referred to as a recoil electron. This term highlights the fact that the electron is effectively "recoiling" away from the interaction point after being struck by the incoming photon.

This process differs from other types of interactions involving photons. For instance, a photoelectron is associated with photoelectric absorption, where an electron is ejected from the atom entirely due to the complete absorption of a photon, while secondary and free electrons refer to electrons resulting from different mechanisms of interaction with materials. In Compton scattering specifically, the terminology focuses on the electron that comes into play during this scattering event, solidifying the use of the term "recoil electron" for the dislodged electron.