Thaddeus, often anglicized as Thaddaeus, is of Greek origin and means 'unquiet' or ' divider'. It is derived from the Greek word 'Thaos', which translates to 'unceasing' or 'divider'. This name has been popular throughout history, notably among early Christian saints. It was also borne by Thaddeus Kosciuszko, a Polish-Lithuanian military engineer and general who fought in the American Revolutionary War.
"The name Thaddius has seen varying popularity over the past century with peaks in the late 1960s to early 1970s and again in the mid-1980s to early 1990s, but it remains relatively uncommon overall."