debt, by furnishing the creditor with a resource to be used in case of failure In the principal obligation. The name is also sometimes given to one who becomes surety or guarantor for another. See First Nat. Bank v. Hollinsworth, 78 Iowa, 575, 43 N. W. 3536, 6L. R. A. 92; Storm v. Waddell, 2 Sandf.