Aristotle’ s discussion of the Ousia are diverse and confusing since there are various definition of the term especially in Metaphysics, Physics and Categories. He refers to it sometimes as the underlying layer, sometimes he means something similar to the meaning of being, and sometimes as essence and quiddity. Hence, the difficulty and disagreement among the translators and interpreters on the best equivalent for Ousia in other languages. In the present paper, after a short historical discussion about Ousia, I examine some common equivalents for the Ousia in Latin and English and attempt to discuss the different reasons for and against each equivalent. My argument, in general, goes for the term Substance, and I will bring 8 reasons to establish the argument.