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. As a literary genre, the memoir is both very old and very new. In his history of the memoir, Ben Yagoda (Memoir: A History, 2009) notes that in the 19th and early 20th centuries, memoirs were usually about someone else -- for example, someone might write a memoir of his relationship with Charles Dickens.