in·stru·men·tal·ist I. \-ələ̇st\noun (-s) Etymology:instrumental (I) + -ist 1. a.: a player of a musical instrument b.: a composer of instrumental music 2.: a proponent of instrumentalism II. \| ̷ ̷ ̷ ̷| ̷ ̷ ̷ ̷ ̷ ̷\adjective : advocating instrumentalism : instrumental