Thaddeus vs. Thaddaeus — What's the Difference?

Thaddeus (Greek Θαδδαῖος, Thaddaios, from Aramaic תדי, Taddai / Aday) is a male given name. It means a heart or courageous heart.As of the 1990 Census, 'Thaddeus' was the 611th most popular male name in the United States, while 'Thad', its diminutive version, was the 846th most popular.

(New Testament) supposed brother of St James; one of the Apostles who is invoked in prayer when a situation seems hopeless