General uses
- Liaison (French), the pronunciation of a word-final consonant due to a following vowel sound in French
- Liaison Dunkerque-Escaut, series of large canals from Dunkerque to Mortagne-du-Nord, France
- Liaison psychiatry, psychiatry that specialises in the interface between medicine and psychiatry
- Affair, an unfaithful or adulterous sexual relationship
- Air Alliance, a Canadian Summit airline whose call sign was “Liaison”
- Collaboration, people working together
Military
- Liaison officer, a military officer who coordinates different forces or national units usually at Staff level
- Liaison aircraft, a small aircraft used by military forces
- Liaison pilot, a World War II pilot who flew liaison aircraft
- Liaison Pilot Badge, a qualification badge issued by the United States Army Air Forces during World War II
- Military liaison missions, Cold War military intelligence missions in Germany
- Military Liaison Element, US special forces personnel attached to embassies
Agencies and individuals
- Liaison Agency Flanders-Europe, an agency of the Flemish Government to enhance the Flemish presence in Europe
- Liaison Committee, a topical committee of the British House of Commons
- Liaison Committee (House of Lords), a select committee of the United Kingdom’s House of Lords
- Liaison Committee on Medical Education, an accrediting body for educational programs at schools of medicine in the United States and Canada