What do you call this: #?
Once you only had to decide whether to refer to it as the “number sign” or the “pound sign” (unless you’re British, in which case “pound sign” refers only to pounds sterling, not weight and is written £).
One of the definitions of “pound sign” in the Oxford English Dictionary is: “U.S. The symbol #, esp. as found on a keyboard or touch-tone telephone; the hash sign.”
The OED has no entry for “hash sign,” or definition of “hash” in this sense, however.
It cites: “1923 W. E. Harned Typewriting Stud. ii. 29/1 Special Signs and Characters‥#‥Number or pound sign; # 10 (No. 10); 10# (ten pounds),” but does not say why # represents “pound.”
A contributor to Language Log (http://languagelog.ldc.upenn.edu/) using the name Sili explains the origin of # for ‘pound’ as a stylized rendering of the abbreviation “lb.” (from Latin libra). Sili provided this illustration from the 8th edition of the Merck Index,1968.
It’s a bit of a stretch, but seems to be the only explanation for associating the symbol with “pound.” I’ve found no reason why it represents “number.”
Now, with everyone tweeting about “hashtags” on Twitter, you may tend to call # a “hash mark.”
According to the New Oxford American Dictionary, hash mark refers to “the symbol #, used esp. for tallying.” That definition doesn’t seem right to me. The usual way to tally is to make four vertical marks and cross them with a diagonal line to show a group of five. NOAD dates the term from the 1980s and gives the origin “probably from hatch, altered by folk etymology.”
The OED defines hatch as ‘An engraved line or stroke; esp. one of those by which shading is represented in an engraving.’ It gives this etymology: < French hache-r to cut, hack, draw lines upon metal, paper, etc., < hache hatchet: see hache n.; compare cross-hatch v.
The most fanciful term for # is octothorpe. I’ve heard it only in queries about the origin of the term.
The NOAD says: “another term for the pound sign (#).
ORIGIN 1970s: of uncertain origin; probably from octo- (referring to the eight points on the symbol) + the surname Thorpe.”
The following is an abbreviated version of the account found at http://www.mootgame.com/ballast/l108.html:
According to Ralph Carlsen (a retired 34-year employee at Bell Labs), the history of the pound sign and the word octothorpe is as follows: In the early 1960s Bell Labs developed the 101 ESS (Electronic Switching System, a pioneer electronic exchange). One of the first installations was at the Mayo Clinic. This PBX had lots of modern features (Call Forwarding, Speed Calling, Directed Call Pickup, etc.), some of which were activated by using the # sign.
A Bell Labs supervisor Don MacPherson went to the Mayo Clinic just before cut-over to train the doctors and staff. During one of his lectures he felt the need to come up with a word to describe the # symbol. Don also liked to add humor to his work. His thought process was as follows:
There are eight points on the symbol so octo should be part of the name.
Don MacPherson, at this point in his life, was active in a group that was trying to get Jim Thorpe’s Olympic medals returned from Sweden. The term thorpe would be unique, and people would not suspect he was making the word up if he called it an octothorpe.
The term was picked up by other Bell Labs people and used mostly for the fun of it. Some of the documents which used the term octothorpe found their way to Bell Operating Companies and other public places. Over the years, Don and I have enjoyed seeing the term octothorpe appear in documents from many different sources.