ˈɪnstɹəmənt ˈɪnstɹəmənt tuːl the means whereby some act is accomplished my greed was the instrument of my destruction science has given us new tools to fight disease address a legal document to write an instrumental score for equip with instruments for measuring, recording, or controlling a device that requires skill for proper use any of various devices or contrivances that can be used to produce musical tones or sounds the semantic role of the entity (usually inanimate) that the agent uses to perform an action or start a process (law) a document that states some contractual relationship or grants some right a person used by another to gain an end