#initialism

• Abbreviation — A word or group of words shortened in writing, usually formed from the initial letters or fragments of the original term; a simplified graphic representation of a concept.
• Acronym — A new word formed from the initial letters or syllables of a phrase, official name, or complex title of an institution or organization, grammatically behaving as an independent and unitary lexical unit (e.g., DEX, UNESCO, NATO). As an adjective, the term describes a word, style, or abbreviative structure built according to this phonetic compaction mechanism.