Acting as an instrument; serving as a means; contributing to promote; conductive; helpful; serviceable; essential or central
He was instrumental in conducting the business.
Applied to a case expressing means or agency—and is generally indicated in English by by or with with the objective; as, the instrumental case. This is found in Sanskrit as a separate case, but in Greek it was merged into the dative, and in Latin into the ablative. In Old English it was a separate case, but has disappeared, leaving only a few anomalous forms. It continues to be used in Slavic languages
Applied to a case expressing means or agency-and is generally indicated in English by by or with with the objective; as, the instrumental case. This is found in Sanskrit as a separate case, but in Greek it was merged into the dative, and in Latin into the ablative. In Old English it was a separate case, but has disappeared, leaving only a few anomalous forms. It continues to be used in Slavic languages
relating to or designed for or performed on musical instruments; "instrumental compositions"; "an instrumental ensemble
Acting as an instrument; serving as a means; contributing to promote; conductive; helpful; serviceable; as, he was instrumental in conducting the business
Instrumental music is performed by instruments and not by voices. a cassette recording of vocal and instrumental music. Instrumentals are pieces of instrumental music. The last track on the CD is an instrumental. a piece of music in which no voices are used, only instruments
relating to or designed for or performed on musical instruments; "instrumental compositions"; "an instrumental ensemble"
{s} helpful, useful, serving to assist; of or pertaining to an instrument; written for or played by musical instruments; of a case which expresses means or agency (Grammar)
In Old English it was a separate case, but has disappeared, leaving only a few anomalous forms