Kimberly Powell over at About.com’s Genealogy section has written an excellent article about the use of “Dit” Names.
Dit names arose out of the French word “to say” or “dire”. From Kimberly:
Found primarily in France, New France (French-Canada, Louisiana, etc.), and Scotland, dit names are essentially an alias tacked on to a family name or surname. Dit in French is a form of the word dire, which means “to say,” and in the case of dit names is translated loosely as “that is to say,” or “called.” Therefore, the first name is the family’s original surname, passed down to them by an ancestor, while the “dit” name is the name the person/family is actually called or known as. Dit names are used by families, not specific individuals, and are usually passed down to future generations, either in place of the orginal surname, or in addition to it.
One of the comments on the post come from Dave Pierce who explains the term “Dit” in a military context:
Dit naming was also used to identify cadres of soldiers. Most often they referred to the
surname of the (military)formation as a hailing recognition factor. In the confusion
of battle, it was always necessary to be ableto direct the formation to a particular action
for succesful maneuvering. As the dit naming would recognize “Andre Jaret Dit Beauregard” it further identified Andre Jaret as a soldier of the unit that was directed by the “Beauregard” commander or possibly by the captain whose surname was BEAUREGARD . These were some of the basic tenets of battlefield tactics that were among the first rules that an officer had to learn.
An article on Dit names by Patrick on a Quebec Research roots web had this statement:
Dit names, therefore, have varied origins: army companies (Verchères,
Sorel, etc.); place of origin (Breton, Langlois, Langevin, Montpelier, etc.);
landscape (Beauregard, Beaulieu, etc.); the ancestor's full name (Gaston
Guay to Gastonguay or Castonguay); ancestor's given name (Richard, Vincent,
Robert, etc.); and no doubt for various other reasons, including vainglory
What I find equally fascinating is that dit names can be found in Scotland. Our Scottish ancestors used names such as Robertson – the son of Robert. Other examples – Robert Bruce who became the King of Scotland.
Another twist on names has been shown in areas where many people had the same name. An academic paper by Nancy Dorian in 1969 entitled A Substitute Name System in the Scottish Highlands uses the term “by-names” to describe a naming system found in Gaelic speakers in the East Sutherland region of Scotland.
The by-names in use in East Sutherland fall into several distinct groups: (1) basic
genealogical; (2) descriptive; (3) derisive; (4) nonsense; and (5) secondary genealogical
patterns built on the second, third, and fourth groups.
Dit names and by-names can complicate your research but by understanding how and why they are used will greatly help you find that missing ancestor.