Sui generis
In sociology, the "sui generis" is what has been externalized, then internalized in the overall public and becomes a part of society that simply exists in its construct. It is not something that is not thought to have been created, because it is imbedded in everyone's way of thinking and being. Instances include the idea of love, or going to school, or clothing belonging to a specific gender. These examples are "sui generis" for they simply exist in society and are widely accepted without thoughts of where they come from or how they were created.
Sui generis
For example, in road traffic law, a statute may require consideration of large vehicles separately from other vehicles. The word "large" is ambiguous per se, but may be considered "heavy". Thus the relevant legislation (in Australian law) contains a section called "Terms used" or "Definitions" that itemises all words considered ambiguous, and confers specific interpretations consistent with natural language. So, this list tells us that "heavy vehicle" means a vehicle with a "GVM" over 4.5 tons;" and "GVM" means "gross vehicle mass"—the maximum loaded mass of the vehicle. Further explanations cover various contingencies. Thus "large" is equivalent to "heavy" and is (for this unique case) clearly defined, "sui generis".