Understandably, Tess still feels a bit too nickname-y; and if you're hoping for a rarer name, Tessa isn't likely to fit the bill for much longer.
- Teresia (teh-RAY-see-ah, Scandinavian; teh-RAY-zee-ah, German)--form of Teresa. Also spelled Theresia.
- Teodosia (teh-oh-DOHS-yah, Italian, Portuguese, Spanish)--"giving to God"
- Tesni (TES-nee, Welsh)
- Tessan (TES-sahn, Swedish)--another form of Teresa [usually only a nickname for Teresia]
- Tethys (TEE-this, TETH-is, Greek)--Greek goddess [Titan] of the sea
- Thais (tah-EES, French, Portuguese)--Russian form is Taisiya (tah-ee-SEE-ah)
- Tressa (TRES-sah, Irish)--Anglicized from Treasa, "strength"