/in'streuh men tay"sheuhn/ , n.
1. the arranging of music for instruments, esp. for an orchestra.
2. the list of instruments for which a composition is scored.
3. the use of, or work done by, instruments.
4. instrumental agency; instrumentality.
5. the science of developing, manufacturing, and utilizing instruments, esp. those used in science and industry.
[ 1835-45; INSTRUMENT (v.) + -ATION ]