Pronunciation: [dˈʌbə͡l hˈa͡ɪfən] (IPA) 
The spelling of "double hyphen" is phonetically transcribed as /ˈdʌbəl ˈhaɪfən/. The first syllable "dub-" is pronounced with a short "u" sound, followed by the stressed vowel "i" in "hy-" and a schwa sound in "-fen". The word "double" refers to the fact that there are two hyphens involved. Hyphens are used in English to join words or parts of words and are important for clarity and understanding.
A double hyphen, also known as a "hyphen-minus," refers to a punctuation mark (--) that combines the characteristics of both a hyphen and a minus sign. It is typically formed by pressing the hyphen key twice in a row on a standard computer keyboard. The purpose of the double hyphen varies depending on its context.
In writing, a double hyphen is primarily used to indicate a range, particularly in numeric expressions. It signifies the interval between two numbers, suggesting that all values within that range are included. For example, the expression "pages 10--15" implies that all pages between 10 and 15, inclusive, are part of a document.
Moreover, a double hyphen occasionally serves as a substitute for an em dash (—) when the latter is unavailable or not natively supported by a particular text formatting or input system. While not technically equivalent, it can be used informally to indicate a pause or an abrupt break in thought within a sentence.
Additionally, in computer programming and command lines, a double hyphen is commonly used to introduce parameters or flags that modify the behavior of a program or command. For instance, "--help" is frequently employed to display a help message or guide on how to use a specific software.
Overall, the double hyphen is a versatile punctuation mark with various uses depending on the context and medium in which it is employed.
The term "double hyphen" does not have a specific etymology as it is a descriptive phrase rather than a standalone word with a defined origin. It simply refers to two hyphens placed together (--). However, the use of the double hyphen in English language can be traced back to the typewriter era.
In typewriters, the dash key was often represented by a single hyphen ("-") instead of a longer dash. To indicate a longer dash on a typewriter, two hyphens were often typed adjacent to each other. This is where the term "double hyphen" originates from. Over time, the use of the double hyphen as a substitute for a longer dash has been adapted in various fields, such as writing, computing, and typesetting. Nowadays, it is commonly known as an "em dash" or simply a "dash" in written English.
