Installation In`stal*la"tion, n. [F. installation, LL. installatio: cf. It. installazione. See Install.] 1. The act of installing or giving possession of an office, rank, or order, with the usual rites or ceremonies; as, the installation of an ordained minister in a parish. On the election, the bishop gives a mandate for his installation. --Ayliffe. 2. (Mech.) The whole of a system of machines, apparatus, and accessories, when set up and arranged for practical working, as in electric lighting, transmission of power, etc.