In music:
* Vocal: If something is instrumental, it means it features only instruments and no singing. The opposite would be vocal, meaning it features singing.
* Non-instrumental: This is a direct opposite, meaning it's not just instruments. It could include singing, spoken word, or other non-musical elements.
In general use:
* Unimportant: If something is instrumental in achieving something, it means it's essential. The opposite would be unimportant, meaning it has little to no impact.
* Non-essential: Similar to unimportant, this suggests that something is not necessary for a desired outcome.
* Passive: If something is instrumental, it implies it is actively involved in causing something. The opposite would be passive, meaning it doesn't contribute to the cause.
* Extrinsic: If something is instrumental, it suggests it's a means to an end. The opposite would be intrinsic, meaning it is valuable in itself, not just for what it can achieve.
To give you a more precise answer, please provide me with the context in which you're using "instrumental."