The name Tristen is of Welsh origin and means "Tumult." The origin is the culture in which the name originated, or in the case of a word--the language in which it most appears.
Originally a male name, it has now crossed over for females, as well. The spelling of Tristan was probably affected by French word "triste" meaning "sad," after the story of Tristan and Isolde, a doomed romance. "Tristan und Isolde," opera by Wagner