instrumental
1. [ adjective ] (music) relating to or designed for or performed on musical instruments
Examples:

"instrumental compositions" "an instrumental ensemble"

Related terms: vocal musical_instrument
2. [ adjective ] serving or acting as a means or aid
Synonyms: implemental
Examples:

"instrumental in solving the crime"

Related terms: helpful
3. [ noun ] (grammar) the case indicating the instrument used in performing the action of the verb
Synonyms: instrumental_case
Related terms: oblique
Similar spelling:   instrument
  instrumentality
  instrumentalist
  instrumentate
  instrumentation
  instilment
  instalment
  instructional
  instillment
  installment
  institute
  instructor
  instructively
  instructed
  instructive
  instruction
  instructress
  instructions
  institutional
  institution
  incidental