The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Quanjer (1 member)
- R-Phrases (2 members)
- REHVA (2 members)
- Railway (17 members)
- Rangtelwoorden (1 member)
- Refrigeration (1 member)
- Religion (2 members)
- Resources (0 members)
- Resources for translators (1 member)
- Reverse engineering (1 member)
- Rijnland (1 member)
- Risk phrases (2 members)
- Romanian (1 member)
- Russian (2 members)
- SAP (3 members)
- SCC (1 member)
- SEO (4 members)
- Sailing (1 member)
- Scaffolding (2 members)
- Scanned (0 members)
- Scanning (0 members)
- Schiphol (1 member)
- Scripting (1 member)
- Sentences (1 member)
- Serge Braudo (1 member)
- Service Level Agreements (1 member)
- Sewing (3 members)
- Shipping (5 members)
- Shoe sorters (1 member)
- Signal words (1 member)
- Slovenian (1 member)
- Software (26 members)
- Solar energy (1 member)
- Spanish (5 members)
- StarDict (1 member)
- Statistics (1 member)
- Stichting Studiebegeleiding Leiden (SSL) (1 member)
- Stock market (1 member)
- Swedish (1 member)
- TT-Software (1 member)
- TU/e (1 member)
- TU Delft (1 member)
- Tag cloud (1 member)
- Tags (1 member)
- Talon (1 member)
- Tax (5 members)
- Technical (25 members)
- Tenders (6 members)
- TermCoord (1 member)
- TermFolders 2.0 (1 member)