an animated corpse, bewitched by Dark magic and commanded to do the bidding of the wizard who is controlling it

(singular), Inferi (plural) – the body of a dead person that a Dark wizard has killed and then reanimated to follow a his orders; Death Eaters were using them to attack people (HBP3, 4, 9, 26, 27, 30)

An Inferius (plural: Inferi) is a corpse controlled through a Dark wizard's spells in the Harry Potter series of books. An Inferius is not alive, but rather just a dead body that has been bewitched into acting like a puppet for the witch or wizard.