A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
U chart: Count-per-unit chart.
Unit: An object for which a measurement or observation can be made; commonly used in the sense of a “unit of product,” the entity of product inspected to determine whether it is defective or nondefective.
Upper control limit (UCL): Control limit for points above the central line in a control chart.
Uptime: See “equipment availability.”