[noncount] :the act or process of making a machine, a service, etc., ready to be used in a certain place :the act of installing something

[singular] :a ceremony in which someone is put in an official or important job

[count] :something (such as a piece of equipment) that is put together and made ready for use

[count] :a place that is used for training soldiers, keeping military supplies and machinery, etc.

[count] :a work of art that usually has several parts (such as a sculpture, lights, and sound) and that is usually shown in a large space