What does Thaddius mean?
Thaddius is an uncommon first name for men. Thaddius is an equivalently rare surname too for all people. (2000 U.S. Census)
Prominent varying forms of Thaddius (#unlisted) are Tad, Thad and Thaddeus (#732 last year). Adoption of these boy names reached its most widespread during 1970-1979 (usage of 0.421%) and is now significantly lower (usage 0.0893%, down 78.8%), with the forms Tad, Thad and Thaddeus becoming less in vogue. Below is a graphed comparison of the usage of Thaddius and related names. (Top 1000 Birth Names Statistics, 2014)