The following categories exist on the wiki, and may or may not be unused. Also see wanted categories.
- Languages: nl, en (1 member)
- Languages: nl, fr (1 member)
- Latin (3 members)
- Law (23 members)
- Legal (0 members)
- Lenntech.nl (2 members)
- Libraries (1 member)
- Librarylingo (1 member)
- Linguistics (1 member)
- Links (2 members)
- Localisation (1 member)
- Logistics (1 member)
- Luggage screening (1 member)
- Lycaeus (1 member)
- MDD (1 member)
- MDR (1 member)
- MISCELLANEOUS (1 member)
- MISSOC (1 member)
- MT (2 members)
- Machine translation (1 member)
- Madaster (1 member)
- Maintenance (2 members)
- Margate (1 member)
- Marketing (1 member)
- Mathematics (7 members)
- Mechanical engineering (2 members)
- MedDRA (1 member)
- Medical (26 members)
- Mental health care (1 member)
- Metalektro (1 member)
- Metallurgy (1 member)
- Michael Beijer (15 members)
- Microbiology (1 member)
- Microsoft (6 members)
- Military (3 members)
- Misc. (10 members)
- Multilingual term search (9 members)
- Multitran (1 member)
- Multitran.com (1 member)
- NCC (1 member)
- NICE (1 member)
- NVWA (1 member)
- Norwegian (1 member)
- Nuffic (4 members)
- O (1 member)
- OCR (0 members)
- OECD (1 member)
- OED (2 members)
- OGL (4 members)
- OHIM (1 member)