Essive case
The essive case, or imilaris case (abbreviated ESS) is one example of a []grammatical case]], an inflectional morphological process by which a form is altered or marked to indicate its grammatical function. The essive case on a noun can express it as a definite period of time during which something happens or during which a continuous action was completed. It can also denote a form as a temporary location, state of being, or character in which the subject was at a given time. The latter meaning is often referred to as the equivalent of the English phrase "as a ___".