instrumental case

Short definition from Wiktionary

Noun

1. 1
   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, Latvian, Slovene, Polish, Ukrainian, Quechua, Russian, Assamese, Tamil, Turkish and Sanskrit. Extinct languages that used the instrumental case include Old English, Old Saxon and Old