Nonfulfilment of an intended usage requirement or reasonable expectation, including one concerned with safety. [3: 2.11]

An item (unit) with one or more defects. Note: In some cases, a series of imperfections or nonconformities may accumulate to make an item (unit) defective. [2: 1.5.9]

In general, the number of terms in a sum minus the number of constraints on the terms of the sum.[1: 2.85]

A control chart for evaluating the process in terms of a dermerit (or quality score), e.g. a weighted sum of counts of variously classified nonconformities. [2: 3.3.11]

The collective term used to describe the availability performance and its influencing factors: reliability performance, maintainability performance and maintenance support performance. Note: Dependability is used only for general descriptions in non-quantitative terms. [4: 191-02-03]

The reduction of the stress ratio on an item. [5: 9.1.11]

A function giving, for every value x, the probability that the random variable X be less than or equal to x: F(x) = Pr [X < x]. [1: 1.4]

Sampling inspection in which the inspection of the first sample of size n1 leads to a decision to accept a lot, not to accept it, or to inspect a second sample of size n2 before making a decision of acceptance or non-acceptance of the lot. The decisions are made according to defined rules. [2: 2.4.2]