a period of time when something (as a machine or factory) is not operating (especially as a result of malfunctions)
downtime详细解释
down.time n.（名词）The period of time when something, such as a factory or a piece of machinery, is not in operation, especially as the result of a malfunction.停工期：某事物，如工厂或机器等，不能正常运作的期间，尤指由发生故障造成的
