stiffen

If your muscles stiffen after a long hike, they become tight and harder to move. But "stiffen" is not only about the body. Cold weather can make your fingers stiffen, fear can make a person stiffen suddenly, and a layer of starch can stiffen cloth.

The word often suggests becoming firm, tight, or tense. It can also be used in a figurative way. A setback might stiffen your resolve, meaning it makes you more determined. In both everyday and figurative use, the idea is the same: something becomes less loose, less soft, or less willing to bend.

To stiffen means to become stiff or to make something stiff. In physical use, it often describes bodies or materials that become firm, tight, or hard to bend. Muscles can stiffen after exercise, fingers can stiffen in the cold, and wet fabric can be stiffened with starch so that it keeps its shape. Dough, glue, or paint can also stiffen as they dry or set.

The word is also common for sudden body reactions. A person may stiffen when they are frightened, offended, or surprised. In that kind of sentence, it suggests a quick change in posture: the body becomes tense and less relaxed. "She stiffened when she heard the door open" shows that instant reaction clearly.

Figuratively, stiffen can mean making feelings, attitudes, or resistance stronger and firmer. Bad news might stiffen opposition. A challenge might stiffen someone's resolve. In these examples, the idea is not about physical hardness but about becoming less ready to give in.

So the word usually carries one central idea: something becomes firmer, tighter, tenser, or more determined than before.