liaison
- A communication link or cooperative relationship between two groups or individuals, especially in an official or professional context.
- A secret or illicit romantic or sexual relationship.
In a sentence
- The embassy appointed a cultural liaison to facilitate communication between the two delegations during the summit.
- The novel's subplot involves a clandestine liaison between a diplomat and a journalist who first met in Vienna.
Usage note. Spelling is the main trap: there is no 'i' after the 'a' — it is '-aison', not '-iation'. Many writers wrongly spell it 'liasion'. The 'n' is silent in the French original but is typically sounded in American English.
Where it comes from
English liaison — “coordinating link or contact” · entered English mid-17th c.
Borrowed from French 'liaison', meaning 'a binding, a connection', from Old French 'lier' (to bind), derived from Latin 'ligare' (to bind, to tie). The word entered English in the mid-17th century initially in military and culinary contexts (in cooking, a liaison is a thickening agent that binds a sauce). The senses of interpersonal coordination and romantic entanglement both developed in English usage (source: Oxford, Etymonline).