1. most rigid or inflexible; hardest to bend or move
Usage: superlative form of ‘stiff’
2. most severe or harsh in terms of punishment, competition, or requirements
Usage: superlative form of ‘stiff’
3. most formal or awkward in manner or behavior
Usage: superlative form of ‘stiff’

Examples

• This cardboard is the stiffest material we have for the project.
• The judge gave him the stiffest penalty allowed by law.
• She faced the stiffest competition of her career in the finals.
• His stiffest shirt made him look very formal at the wedding.
• The new regulations impose the stiffest requirements yet.
• That was the stiffest handshake I’ve ever received.
• The stiffest breeze of the day finally cooled us down.