Duress is pressure that is not fair — threats, force, or fear used to make you do something you would not choose. The old meaning sits in the Latin: hardness. Someone is being hard on you until you give in. In real English you almost always meet it in the phrase under duress: you signed the paper under duress; you confessed under duress. Lawyers use it a great deal. If you acted under duress, the law may say the act was not truly your free choice. Though actually, in everyday talk people stretch it: “I only went to the party under duress” can mean friends pushed you, not that anyone broke the law. That looser use is half-joking. The serious use is illegal or unfair threats. A verb “to duress” exists in some legal writing, but ordinary speakers almost never use it.