Part of the IT standards and organizations glossary: The Stefan-Boltzmann constant, symbolized by the lowercase Greek letter sigma (), is a physical constant involving black body radiation.A black body, also called an ideal radiator, is an object that radiates or absorbs energy with perfect efficiency at all electromagnetic wavelength s.art of the IT standards and organizations glossary: The Stefan-Boltzmann constant, symbolized by the lowercase Greek letter sigma (), is a physical constant involving black body radiation.
Definition of memoir for English Language Learners. memoirs : a written account in which someone (such as a famous performer or politician) describes past experiences.
memoir (plural memoirs) 1  An autobiography; a book describing the personal experiences of an author. 2  A biography; a book describing the experiences of a subject from personal knowledge of the subject or from sources with personal knowledge of the subject. 3  Any form of narrative describing the personal experiences of a writer.