The symbol # has several common names, and one of the most interesting is octothorpe. In everyday use, many people never hear that term, but it is a real name for the symbol.
The exact origin of octothorpe is not fully certain. A common explanation is that octo refers to the symbol’s eight points, while thorpe was added later as part of the name. What matters most for learners is that the same symbol can have different names in different contexts.
- Pound sign: in American English, this often appears before a number, as in #5.
- Number key: on a phone keypad, someone might say Press #.
- Hashtag marker: online, it creates tags such as #Writing.
These names are context based, not separate symbols. The mark is still the same #. In British English, people are often more likely to call it a hash, especially when talking about phones, computers, or social media. So if you hear octothorpe, pound sign, number key, or hash, the meaning usually depends on where the symbol appears.