"Mimesis" ("μίμησις" from "μιμεîσθαι") in its simplest context means imitation or representation in Greek.
Both Plato and Aristotle saw, in mimesis (Greek μίμησις), the representation of nature. However, Plato thought all creation was imitation, and so God's creation was an imitation of the truth and essence of nature, and an artist's re-presentation of this God-created reality therefore was twice-removed imitation.
Aristotle thought of drama as being "an imitation of an action", that of tragedy as of "falling from a higher to a lower estate", and so being removed to a less ideal situation in more ''tragic'' circumstances than before. He posited the characters in tragedy as being better than the average human being, and those of comedy as being worse.
Aristotle's most well known work on this subject is his Poetics.
Walter Kaufmann in ''Tragedy and Philosophy'' Ch.II suggests that we translate mimêsis in Aristotle’s Poetics as “make-believe”.
Michael Davis, a translator and commentator of Aristotle writes: