Being very important, or key to something.
Having or containing the centre of something.
Being in the centre.
Exerting its action towards the peripheral organs.
centre
essential or central; of great importance or relevance.
Pertaining to, made by, or prepared for an instrument, especially a musical instrument (rather than the human voice).
Applied to a case expressing means or agency, generally indicated in English by by or with with the objective.
Serving as an instrument, medium, means, or agency.
The instrumental case.
A composition written or performed without lyrics, sometimes using a lead instrument to replace vocals.