The name Tristen means Tumult and is of Welsh origin. Tristen is name that's been used by parents who are considering unisex or non-gendered baby names--baby names that can be used for any gender.
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