verb🔗ShareTo make stiff."The cold weather caused the paintbrush to stiffen, making it difficult to use. "materialprocessChat with AIVocabulary GamePractice Reading
verb🔗ShareTo become stiff."After sitting at my desk all day, my back was stiffening. "bodyphysiologyChat with AIVocabulary GamePractice Reading
noun🔗ShareAn item, material or feature that makes something stiffer."The stiffening in the cardboard box made it strong enough to hold the fragile vase. "materialitemtechnicalChat with AIVocabulary GamePractice Reading
