It’s not a popular name.
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.
I recall the name. I recall Thaddeus Potgalki. I have misspelled it. He was a hippie in my high school class. Mid 1960’s – duh! He had a beard before I had arm hair. I recall my chemistry teacher Mr. Schindler slowly savor his name as he pronounced it. He next appears in my memory in my high school English class when he gave a thundering delivery of a poetic piece. He was destined for drama as I was for science and medicine. I hope he did well.