in·stall / inˈstôl/ (Brit. also in·stal) • v. [tr.] 1. place or fix (equipment or machinery) in position ready for use: we're planning to install a new shower.2. place (someone) in a new position of authority, esp. with ceremony: he was installed as music director at the Cathedral of St. Barbara in Cracow. ∎  establish (someone) in a new place, condition, or role: Ashley installed herself behind her table.DERIVATIVES: in·stall·er n.

install
1. To take software from the distribution files, which can be on floppy disks, CD-ROM, tapes, or on a remote networked computer, and place it in its permanent location from where it will be executed. The installation process is not just a straight copy as it involves unpacking compressed files, configuring the software to suit its environment, and perhaps allowing the installer to choose how much of the software to install. A typical installation program will offer choices of minimum, custom, or full installations.

2. To fit new hardware features to a computer.

install invest with or place in an office, orig. by placing in an official stall XVI; (after F.) to place in position XIX. — medL. installāre, f. IN-1 + stallum STALL1; cf. (O)F. installer.
So installation XVII. — medL. Hence instalment¹ U.S. installment installation. XVI.