Θαδδαῖος, Thadaios, Thaddaeus: Possibly, from the Aramaic name Thaddai, meaning heart. Alternatively, an  Aramaic form Θεόδωρος (Theodore).

Θεοβάλδος, Theobald: Of a powerful people. From the Germanic theud (people) and bald (bold).

Θεοδώριχος, Theodoricus, Theodoric: Ruler of people. From the  Germanic  theud (people) and ric  (ruler).

Θίλδα, Tilda, Mathilda: Might in battle. From the  Germanic maht  (might) and hild  (battle).

Θίλδη, Tilde, Mathilde: Might in battle. From the  Germanic maht  (might) and hild  (battle).

Θωμαή, Thomae: Female form of Θωμάς (Thomas). From the Aramaic name תָּאוֹמָא  (Taoma), meaning twin. 

Θωμαΐδα, Thomaida: Female form of Θωμάς (Thomas). From the Aramaic name תָּאוֹמָא  (Taoma), meaning twin. 

Θωμαΐς, Thomais: Female form of Θωμάς (Thomas). From the Aramaic name תָּאוֹמָא  (Taoma), meaning twin. 

Θωμᾶς, Thomas:  From the Aramaic name תָּאוֹמָא  (Taoma), meaning twin.

© Paul Pan