* Inflexible: Means not flexible, rigid, or unyielding.
* Hyperflexible: Means excessively flexible.
* Superflexible: Means extremely flexible, beyond normal limits.
* Multiflexible: Means able to bend or adapt in multiple ways.
* Semi-flexible: Means somewhat flexible, not entirely rigid.
* Pre-flexible: Means something that is designed to be flexible before it is used (less common, but possible).
The best prefix to use will depend on the specific context and meaning you want to convey.