stiffening

(noun) the act of becoming stiff. Example: "Stiffening his shoulders, he prepared to advance."

(noun) the process of becoming stiff or rigid. Synonyms: rigidifying, rigidification.

(verb) become stiff or stiffer. Synonyms: stiffen. Example: "He stiffened when he saw his boss enter the room."

(verb) make stiff or stiffer. Synonyms: stiffen. Example: "Stiffen the cream by adding gelatine."

(verb) restrict. Synonyms: stiffen, tighten, tighten up, constrain. Examples: "Tighten the rules." "Stiffen the regulations."