liaisonn.[F., fr. L. ligatio, fr. ligare to bind. See Ligature, and cf. Ligation.]1. A union, or bond of union; an intimacy; an interrelationship.()2. An illicit sexual relation between a man and a woman; a sexual afffair.()3. A process of communication between parts of an organization or between two organizations acting together for a common purpose.()4. A person whose function it is to maintain such communication.()5. (Phonetics) A pronunciation of a consonant sound that would be otherwise silent, such as the final consonant of certain French words, when the following word begins with a vowel sound.()n.[F. liane; prob. akin to lien a band, fr. L. ligamen, fr. ligare to bind. Cf. Lien, n. ] (Bot.) A luxuriant woody plant, climbing high trees and having ropelike stems. The grapevine often has the habit of a liane. Lianes are abundant in the forests of the Amazon region.()