Number sign

It is so used in the U.S. and Canada, where No. would be used in the UK (and also Canada since the influence comes from both directions).

Unicode value: x'0023'.

ASCII value: 35

Hex value: 23

It has many other names (and uses) in English. (Those in bold are listed as alternative names in the Unicode documentation.)

• comment sign
  • from its use in some programming languages, e.g. Perl, to introduce comment text
• crosshatch
  • resemblance
• crunch
  • ?
• fence, gate, grid, gridlet
  • resemblance
• hash / hash mark / hash sign
  • ?
• hex
  • from its use to denote hexadecimal values in some markup and programming languages; e.g., HTML
• octothorn
  • William Sherk in 500 Years of New Words (1983), p. 272, has the following entry: "Octothorn, The number sign (#); so called because there are eight points, or thorns, sticking out of it ... ."
• octalthorpe / octothorp / octothorpe
  • disputed origin: maybe (i) thought to look like a group of eight fields surrounding a village (Norwegian thorpe) [¿and ostensibly used in cartography?]; or (ii) octo- for its eight points, plus the surname Thorpe – see Weird Words entry [1] (http://www.quinion.com/words/weirdwords/ww-oct1.htm) (but see the World Heritage Dictionary entry [2] (http://www.bartleby.com/61/88/O0028850)); or (iii) The Pasadena Star-News reported October 20, 1981, p. A-3, "According to the folks at Bell Laboratories in New Jersey, a rumor started in the 1960's or earlier ... that this symbol is called an octothorpe. One story has it that the rumor was started ... by one Charles B. Octothorpe." In another Star-News article on November 3, 1982, p. B-4, the word is written without the final e and refers to John B. Octothorp.
• pig pen
  • resemblance
• pound / pound sign
  • Used as the symbol for the pound avoirdupois in the U.S. (and Canada?) (where lb. would be used in the UK)
    • Keith Gordon Irwin in, The Romance of Writing, p. 125 says: "The Italian libbra (from the old Latin word libra, "balance") represented a weight almost exactly equal to the avoirdupois pound of England. The Italian abbreviation of lb with a line drawn across the letters was ... used for both weights. The business clerk's hurried way of writing the abbreviation appears to have been responsible for the # sign used for pound."
  • Used in the U.S. (and Canada?) on touch-tone telephones – "Please press the pound key!"
• sharp
  • resemblance to the glyph used in music manuscripts; so called in the name of Microsoft's new programming language, C#
• square
  • so called in the UK, on touch-tone telephones – "Please press the square key!" – despite several possible ambiguities
• tic-tac-toe / tictactoe
  • resemblance
• widget mark
  • ?

The pronunciation of # as `pound' is common in the U.S. but a bad idea; Commonwealth has its own, rather more apposite use of `pound sign' (confusingly, on British keyboards the pound graphic happens to replace #; thus Britishers sometimes call # on a U.S.-ASCII keyboard `pound', compounding the American error). The U.S. usage derives from an old-fashioned commercial practice of using a # suffix to tag pound weights on bills of lading. The character is usually pronounced `hash' outside the U.S. There are more culture wars over the correct pronunciation of this character than any other, which has led to the ha ha only serious suggestion that it be pronounced `shibboleth' (see Judges 12:6 in an Old Testament or Tanakh).

In Hebrew, called:

• sulamit (i.e., 'ladder')

References (as numbered above)

1. World Heritage Dictionary
   • Entry for this symbol: <http://www.quinion.com/words/weirdwords/ww-oct1.htm > - valid 22nd of May 2003
2. Weird Words
   • Entry for this symbol: <http://www.bartleby.com/61/88/O0028850 > - valid 22nd of May 2003