- BAK stands for Backup (File Name Extension)
- BAK stands for Backspace
- BAK stands for Bundesarchitektenkammer
- BAK stands for Back At Keyboard
- BAK stands for Bundesamt für Kultur (German: Federal Office for Culture; Switzerland)
- BAK stands for Biking Across Kansas (bicycle tour)
- BAK stands for Bauartklasse (German insurance term)
- BAK stands for Berliner Arbeitskreis Information (German)
- BAK stands for Basic Aeronautical Knowledge
- BAK stands for Betrayal At Krondor (computer game)
- BAK stands for Bundesaufsichtsamt für das Kreditwesen (German banking supervisory board)
- BAK stands for Baku, Azerbaijan – Baku (Airport Code)
- BAK stands for Blut Alkohol Konzentration (German: blood alcohol level)
- BAK stands for Binary Adaption Kit
- BAK stands for Beitragsanpassungsklausel (German; legal insurance)
- BAK stands for Bewußtsein, Atmung, Kreislauf
- BAK stands for Bosomtwe-Atwima-Kwanwoma (district; Ghana)
- BAK stands for Bouviers d’Australie et des Kelpies (French: Australian Kelpie and Cattle Dog; dog club)
- BAK stands for Barrier Arresting Kit
- BAK stands for Bilateral Above Knee (amputation)
- BAK stands for Biohybrid Artificial Kidney
BAK