is a specific kind of: inelasticity.

is a broader term that covers: inflexibility, inflexibleness.

derivation: ossify, petrify, rigidify | rigidify | rigid, stiff | fixed, rigid, set.

is a specific kind of: unadaptability.

is the opposite of: flexibility, flexibleness.

derivation: ossify, petrify, rigidify | inflexible | inflexible, sturdy, uncompromising | inflexible, rigid, unbending | rigid, strict.