CMMS & maintenance glossary
Plain-language definitions of the terms maintenance teams use every day.
Asset
Any piece of physical equipment that a maintenance team is responsible for keeping in working order — a motor, a pump, a vehicle, an HVAC unit, a refrigerator, a server rack.
Mean time between failures(MTBF)
The average time an asset operates between failures. A higher MTBF means a more reliable asset.
Mean time to repair(MTTR)
The average time it takes to restore an asset to working order after a failure. A lower MTTR means a more responsive maintenance operation.
Preventive maintenance(PM)
Maintenance work scheduled in advance — based on time, usage, or condition — to keep an asset running before it fails, instead of reacting after a breakdown.
Procedure
A documented sequence of steps a technician follows to perform a specific maintenance job — typically with checkboxes, form fields, and required evidence (photos, signatures, readings).
Reactive maintenance
Maintenance performed after an asset has already failed or stopped working as expected. Also called 'run-to-failure' or 'breakdown maintenance'.
Work order
A document (digital or paper) that authorizes and records a specific maintenance job, including who is responsible, what needs to be done, on which asset, and what was actually performed.