Eng (THAD-dee us; TAD-dee-us)
The name is a Greek transliteration of the Aramaic male name, Thaddai, which is argued to either be derived from an Aramaic word meaning heart or to be an Aramaic version of the Greek male name, Theodore.
In the New Testament, the name is borne by one of the 12 Apostles, known as Jude Thaddeus, especially among Catholics. He is popularly known as St. Jude, St. Thaddeus or St. Jude Thaddeus and is venerated as the patron saint of lost causes.
In American history, the name was borne by the Polish borne revolutionary hero, Taddeusz Kosciuszko (1746-1817).
In 2010, Thaddeus was the 983rd most popular male name in the United States. In Slovenia, Tadej was the 58th most popular male name of 2010.
The name Tadeusz, has always been a popular male name in Poland, it is the name of the title character of one of Poland’s beloved literary classics, Pan Tadeusz by Adam Mickiewicz.
Other forms of the name include:
T’adeos Թադէոս (Armenian)
Tadevuš (Belarusian) (tah-DEH-voosh)
Tadija (Croatian) (TAH-dee-yah)
Tadeáš (Czech/Slovak) (tah-deh-AHSH)
Thaddée/Taddée (French) (tah-DAY)
Thaddäus (German) (tad-DAY-oos)
Thaddaeus/Thaddaios Θαδδαιος (Greek: Biblical)
Tádé (Hungarian) (TAH-day)
Taddeo (Italian) (tah-DAY-o)
Tadas (Lithuanian) (TAH-dahs)
Tadeušas (Lithuanian) (TAH-deh-oo-SHAHS)
Tadeusz (Polish) (tah-DAY-oosh)
Faddei/Faddey Фаддей (Russian) (FAD-day)
Tadej (Slovene) (tah-DAY)
Tadeo (Spanish) (tah-DEY-o)
Common English diminutives are Tad, Thad and Teddy. In Polish it is Tadek.
The designated name-days are: June 25 (Slovakia), October 28 (Poland) and October 30 (Czech Republic),
Feminine forms include the Italian, Taddea and the Polish, albeit rare, Tadea.