One not made voluntarily, but exacted by duress, threats, the enforcement of legal process, or unconscionably taking advantage of another. Shaw v. Woodcock, 7 Barn. & C. 73; Beckwith v. Frisbie. 32 Vt. 565; State v. Nelson, 41 Minn. 25, 42 N. W. 548, 4 L. R. A. 300; Lonergan v. Buford, 148 U. S. 581. 13 Sup. Ct. 684, 37 L. Ed. 569