SOOTHFAST a. 2 definitions
unded upon, the thruth; true; genuine; real; also, truthful; faithful. [Archaic] -- Sooth"fast`ness, n. [Archaic] "In very soothfastness." Chaucer. Why do not you . . . bear leal and soothfast evidence in her behalf, as ye may with a clear conscience! Sir W. Scott.