The octothorpe definition is the name often given to the # symbol, familiar on phones and social media.
Most people call it a hash, pound sign, or hashtag. Few know why the odd word octothorpe stuck around.
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What Does octothorpe definition Mean?
At its core, the octothorpe definition names the character #, a gridlike glyph made of two horizontal and two vertical strokes crossing. The symbol has been used to mean number, weight, and, more recently, a way to group topics online.
Put simply, it is the character on your keyboard right above the 3 in many layouts, and it acts differently depending on context and culture.
Etymology and Origin of octothorpe definition
The story behind the octothorpe definition is part technical folklore and part linguistic curiosity. Engineers at Bell Labs reportedly coined the term in the 1960s, and the name stuck because it sounded whimsical and a bit mysterious.
There are competing origin stories, which include a joke about the nine fields of information on old teletypes and a tribute to an Olympic athlete named Thorpe. If you want a readable overview of the symbol’s history, see the Wikipedia on octothorpe and the entry at Merriam-Webster.
How octothorpe definition Is Used in Everyday Language
The octothorpe definition moves easily between formal notations and casual speech. It can say ‘number’ on printed forms, act as a shorthand for pounds of weight, or mark topics in social media.
1. On a form: ‘Acct no. 42#’ where the # signals the number; people might still call it the octothorpe.
2. On a phone menu: ‘Press # to finish’, and the # key is called the octothorpe by some technicians.
3. In code: ‘print(“# comment”)’ depending on language, but developers often refer to it by its name or simply as hash.
4. Social media: ‘#summer’ creates a tag, which most users call a hashtag rather than octothorpe.
octothorpe in Different Contexts
Context changes everything. Telephone technicians and older printed forms favored the term pound sign or number sign. Programmers often say hash, and social media users use hashtag when the symbol forms part of a topic label.
Legal documents sometimes used # to abbreviate ‘number’ for addresses and citations. In the United Kingdom, calling it ‘hash’ is common, whereas in the United States older speakers might still say ‘pound’.
Common Misconceptions About octothorpe definition
One common mistake is believing octothorpe is the original or formal name for the symbol. In reality, octothorpe is a relatively modern, playful name layered on top of older terms like pound sign and number sign.
Another misconception is that the symbol always indicates a topic. That is a social media innovation. Historically, the symbol had many uses long before hashtags emerged.
Related Words and Phrases
Words that orbit the octothorpe include hash, pound sign, number sign, and hashtag. Each term carries a slightly different flavor and suggests a typical use case.
For more on nearby terms, check these entries: hash symbol meaning and hashtag meaning. These pages unpack modern usage versus older typographic practice.
Why octothorpe definition Matters in 2026
The octothorpe definition matters because the symbol sits at the intersection of language, technology, and culture. Its uses tell a short history of changing communication tools, from telephones to social networks.
Designers, editors, and communicators should know the word and its connotations. If you label something with # today, you are tapping a symbol with decades of layered meaning.
In closing, octothorpe definition is a small term with a big backstory, one that reveals how users name the tools they rely on. Want a deeper etymological dive? The Oxford English Dictionary and other scholarly sources track the word’s first appearances and changing uses.
For further reading, see Oxford English Dictionary and explore technical notes in telephony archives linked from academic sources.