1. Serving as a means or agency; implemental: was instrumental in solving the crime.
2. Of, relating to, or accomplished with an instrument or tool.
3. Music Performed on or written for an instrument.
4. Grammar Of, relating to, or being the case used typically to express means, agency, or accompaniment.
5. Of or relating to instrumentalism.
a. Grammar The instrumental case.
b. A word or form in the instrumental case.
2. Music A composition for one or more instruments, usually without vocal accompaniment.
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2020 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.