initialisme

Initialisme is a type of abbreviation formed from the initial letters of the words in a multiword term or phrase. It is typically pronounced letter by letter, rather than as a single word. Examples include NATO, FBI, and HIV. When the letter string can be spoken as a word, such as NASA or radar, the item is often called an acronym, though the boundary between initialisms and acronyms is not always strict in practice. Some usage guides reserve "acronym" for pronounceable units and label other cases initialisms.

Formation and orthography: Initialisms are usually written in uppercase letters, though some fields use lowercase or mixed case for readability (e.g., iPhone, GPS in all caps). Punctuation varies; many writers omit periods (U.S., NASA vs US NASA). In formal writing, the full term is introduced first with the abbreviation in parentheses, then the abbreviation is used alone.

Usage and scope: Initialisms are common in technical, governmental, and organizational contexts where long names recur. They save space, aid readability, and reflect institutional practice. They may become lexicalized over time and pass into common words (e.g., laser, radar). On first mention, ensure audience familiarity; avoid excessive proliferation.

Language and terminology: The term initialisme is used in some languages (notably in French and Dutch) to contrast with "sigle" or "acronyme," reflecting subtle distinctions about pronounceability. In English, the umbrella term "initialism" and "acronym" are often used with overlapping meanings. References and style guides vary on classification, punctuation, and capitalization.