Initialism

An initialism is an abbreviation formed by using the first letters, or initials, of a series of words, for example "BBC", or "IBM". The term initialism is often used by those who make a sharp distinction between an initialism and an acronym; they reserve the term acronym for cases when the letters form a pronounceable word, like "NATO" or "AIDS", and use the term initialism when they do not. (Thus, by this definition, BBC ("Bee Bee See") is an initialism, while NATO ("Naytow") is an acronym.) Others do not make this distinction, and use the terms interchangeably (though the term acronym is used much more frequently in this case).

See also: List of initialisms, List of general acronyms