The word "dipl-" is a commonly used prefix in English which usually indicates a form of official credential or documentation. Some synonyms for "dipl-" include "certificate," "credential," "license," "qualification," and "testament." For instance, a "diploma" is a certification or proof of a degree or completion of an educational program, while a "certificate" can serve the same purpose. Similarly, a "license" is an official authorization to perform a particular activity, such as driving or practicing medicine. In short, all words with "dipl-" prefix have a common characteristic of referring to formal documentation or proof of accomplishment or attainment in a particular field.