By definition, a defect is defined, according to the "Glossary of Metallurgical Terms and Definitions" from ASM's Metals Reference Book (3rd Edition), as follows:
1. A discontinuity whose size, shape, orientation or location makes it detrimental to the useful service of the part in which it occurs.
2. A discontinuity or discontinuities which by nature or accumulated effect (for example, total crack length) render a part or product unable to meet minimum applicable acceptance standards or specifications. This term, therefore, designates rejectability.
In my brazing seminars, I often print in large letters on the board in front of the class: "DEFECT = REJECT"
Please be sure to use the correct terminology when referring to imperfections such as voids, depressions, discontinuity, erosion, pinholes, anomalies, etc. ONLY use the word "defect" when that imperfection will result in the failure of the part or component to perform in an acceptable manner for which it was designed.