The Collaborative International Dictionary of English v.0.48:
Sassenach \Sas"sen*ach\, n. [Gael. sasunnach.] A Saxon; an Englishman; a Lowlander. [Celtic] --Sir W. Scott. [1913 Webster] SassolinWordNet (r) 3.0 (2006):
Sassenach n 1: the Scots' term for an English person