adjective
rigid
RIJ-id/ˈrɪdʒɪd/
Unable to bend readily.
The rigid metal ruler stays straight as someone tries to bend it.

Etymology
Latin rigidus joined physical stiffness with severity. That connection carries into English: a rigid object will not bend, while a rigid person or rule will not yield or adapt.
In context
A busk was a long, flat piece of wood or bone, slid down the front of the bodice to keep the figure straight and rigid and unbending.
More examples
- The poster needs a rigid backing to keep it flat.
- Cold temperatures make the rubber hose more rigid.
- A rigid brace keeps her wrist from bending.
Forms
rigid · more rigid · most rigid
rigidity noun — The quality of resisting bending or deformation.
Similar words
- stiff
- Often allows some bending, though only with effort.
- inflexible
- Emphasizes inability to bend rather than resistance to bending.