octothorpe

n. A name for the hash or square symbol (#), used mainly in telephony and computing

If you’re like most people, you’ve perhaps never even heard of the word “octothorpe.” If you aren’t American, you’ve almost certainly never used the term, and likely rarely hear it in polite conversation. Even among the people who originated the term, “octothorpe” is one of those curious linguistic complexities quickly replaced by coarser variations such as “hash,” “pound sign,” and “number sign.”

Yes, curiously enough, “octothorpe” is the term for the # sign common to all keyboards and touchtone phones. Moreover, it’s acquired a slew of variant spellings, likely due to the way in which speech naturally garbles its constituent parts: it’s known variably as octothorp, octothorpe, octathorp, octatherp, octothorn, and octalthorpe. In fact, as sources document, its origins aren’t at all clear. We may surmise relatively easily the octo- portion, but the variant thorp[e]/thorn/therp is attributed to any one of a number of shibboleths, inside jokes, and arbitrary euphonia. The term, like the symbol’s use within Telecom, like originated somewhere within Bell Labs, along with its sibling symbol, the asterisk, one of two non-alphanumeric symbols which have risen to prominence via touchtone phones. Whatver its origin, this particular synonym has fallen distinctly out of favor, even in its ostensible country of origin—the official Unicode designation for the character is “number sign.”

Its origin has been described separately by Ralph Carlsen as being a combination of “eight-pointed” and the last name of Olympian Jim Thorpe (and spelled “octothorpe”). Donald Kerr, supposedly part of (in charge of?) the committee at Bell in charge of choosing and naming the non-numeric symbols to be used on Bell’s phones, claims that two former colleagues coined “octatherp” as a joke.

The asterisk, at least etymologically, has a much clearer lineage: it’s from the Greek ἀστερίσκος, by way of the Latin asteriscum (“little star”). Some sources date its use typographically to the beginnings of the printed word, when it was used to denotes dates of birth. In various cultures and alphabets, the “star” character appears, though it has different meanings depending on where you find it. It, too, was co-opted as a symbol of the first touchtone telephone, alongside its eight-pointed friend, though of course it has garnered specific meanings in every industry: in programming, it’s considered a “wildcard”; similarly, it has a slew of separate meanings in mathematical notation. Because the the word asterisk’s relative complexity in pronunciation, it’s generally been referred to as a “star,” especially in the context of phones.