Emily Dickinson Lexicon

IN'STRU-MENT, n. [Fr. from L. instrumentum, from instruo, to prepare; that which is prepared.]

1. A tool; that by which work is performed, or any thing is effected; as a knife, a hammer, a saw, a plow, &c. Swords, muskets and cannon are instruments of destruction. A telescope is an astronomical instrument.
2. That which is subservient to the execution of a plan or purpose, or to the production of any effect; means used or contributing to an effect; applicable to persons or things. Bad men are often instruments of ruin to others. The distribution of the Scriptures may be the instrument of a vastly extensive reformation in morals and religion.
3. An artificial machine or body constructed for yielding harmonious sounds; as an organ, a harpsichord, a violin, or flute, &c., which are called musical instruments, or instruments of music.
4. In law, a writing containing the terms of a contract, as a deed of conveyance, a grant, a patent, an indenture, &c.; in general, a writing by which some fact is recorded for evidence, or some right conveyed.
5. A person who acts for another, or is employed by another for a special purpose, and if the purpose is dishonorable, the term implies degradation or meanness.