Inhumans

Inhumans are genetically modified humans that are enhanced in strength, agility, intelligence and increased semblances. Inhumans are created by adding a portion of Immortal blood to a human. All of the Inhumans are created by a scientist called Reginald.

As a term
According to Miranda Sapphire, when she explained the Fatality Force, an Inhuman does not necessarily have to be an Inhuman, but a being of enhanced abilities.

Trivia

 * Inhumans are based off the MARVEL species of the same name, prominently shown in the MARVEL TV Show Agents of S.H.I.E.L.D