stiffening
nounUK /ˈstɪfənɪŋ/
US /ˈstɪfənɪŋ/
Stiffening is when something becomes hard and does not bend easily.
The stiffening of the cardboard made the box strong.
OTHER MEANINGS
2. A material added to cloth to make it hold its shape.
The tailor used stiffening in the collar of the shirt.
3. The act of making a part of the body or a joint less able to move.
He felt a stiffening in his neck after sleeping badly.
4. Becoming more strict or severe.
There was a stiffening of the rules after the accident.