adjective
stiff
STIF/stɪf/
Resistant to bending or yielding.
The stiff boot sole resists the man's efforts to bend it.

Etymology
Old English stif described something rigid and not easily bent. That physical resistance also underlies the extended senses of awkward movement and a manner lacking ease.
In context
unlike hard rubber which can become stiff in low temperatures soft rubber retains its flexibility
More examples
- My knees feel stiff after the long drive.
- Our team faces stiff competition in the finals.
- Drivers face stiff fines for speeding near schools.
- His stiff greeting makes everyone feel awkward.
Forms
stiff · stiffer · stiffest
stiffen verb — To become or make less flexible.
stiffness noun — The quality of resisting bending or movement.
Similar words
- rigid
- Suggests almost no bending, rather than merely resisting it.
- inflexible
- Emphasizes inability to bend or unwillingness to adapt.
- hard
- Emphasizes resistance to pressure or scratching, not necessarily bending.