1 [uncountable]T when someone fits a piece of equipment somewhere :
the installation and maintenance of alarm systems
the installation and maintenance of alarm systems2 [countable]T a piece of equipment that has been fitted in its place :
The whole computer installation was nearly new.
The whole computer installation was nearly new.3 [countable]TIPM a place where industrial or military equipment, machinery etc has been put :
nuclear installations
nuclear installations4 [countable] a piece of modern art which can include objects, light, sound etc
5 [uncountable] formalBO the ceremony of putting someone in an important job or position :
the installation of the new bishop
the installation of the new bishop