maintenance

As a noun maintenance is

actions performed to keep some machine or system functioning or in service.

As nouns the difference between maintenance and optimization

is that maintenance is actions performed to keep some machine or system functioning or in service while optimization is the design and operation of a system or process to make it as good as possible in some defined sense.

As nouns the difference between operation and maintenance

is that operation is the method by which a device performs its function while maintenance is actions performed to keep some machine or system functioning or in service.

Maintenability is often a misspelling of maintenance.

Maintenability has no English definition.

As a noun maintenance

is actions performed to keep some machine or system functioning or in service.

As nouns the difference between custodian and maintenance

is that custodian is a person entrusted with the custody or care of something or someone; a caretaker or keeper while maintenance is actions performed to keep some machine or system functioning or in service.