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.
While an autobiography typically focuses on the life and times of the writer, a memoir has a narrower, more intimate focus on his or her own memories, feelings and emotions. Memoirs have often been written by politicians or military leaders as a way to record and publish an account of their public exploits.