The importance of keeping - if possible - a clear, one-to-one relation between concept and term when classifying terms has often been addressed in the literature on terminology.
Things can be more complicated in practice. For example, two of the most common problems observed when trying to classify terms is that there are synonymy and homonymy relations among terms and both phenomena could be a tough nut to crack when trying to keep a one-to-one structure in a terminology database.
In terminology, synonymy can be defined as the relation between different terms representing only one concept in one language, e.g. "sodium chloride" and "NaCl". Different terms are synonyms for example when their definitions have the same meaning - often one of the terms is used in general or by a specific user as the "preferred" term. [Source: adopted from DIN 2342, p. 3]
Considered also as synonyms are:
- Terms with different spelling (hyphen, joining elements, etc.)
- The term's full form compared to its short form
- Abbreviations of a term
- Acronyms