What is "instrumental case"

n. (context grammar English) A noun case used to express means or agency—and is generally indicated in English by '''by''' or '''with''' with the objective. Languages that use the instrumental case include Armenian, Serbo-Croatian, Czech, Dyirbal, Georgian, Slovene, Polish, Quechua, Russian and Sanskrit.

The instrumental case ( abbreviated or ) is a grammatical case used to indicate that a noun is the instrument or means by or with which the subject achieves or accomplishes an action. The noun may be either a physical object or an abstract concept.