May and the Slash

When punctuating, medieval monks were prone to use the same sign for different things and different signs for the same thing. In place of the punctuational dots that were in widespread use, some monks penned a slash, a mark they called a ‘virgula’, a twig. The slash served sometimes as a comma, sometimes as a colon, and ‘sometimes’, says Malcolm Beckwith Parkes, ‘with an application which falls somewhere between the two’.

Monkish punctuation served monkish purposes well, but in the 1450s moveable type came to Europe, and that called for new forms of punctuation. The new forms took time to settle. In the 1470s, William Caxton used the slash as his comma sign, and, to this day, the French call the comma the ‘virgule’, but the French, like the English, no longer mark a comma with a slash. Printers in both lands give the comma the semicircular form that Aldus Manutius gave it in the 1490s. By 1600, the English had stopped using the slash as a comma, and the slash took on new jobs.

The most recent function of the slash is the ‘slash notation’ by which the hypertext transfer protocol (http) introduces an IP address with a colon followed by double slashes. The protocol then subdivides the IP address by single slashes:

The slash is, says, commonly ‘used as the division operator in programming.’ It is its use in internet addresses that has caused this mark to be called a ‘slash’ today. Until the 1970s, ‘slash’ was the American English name for the mark that has been called variously the virgule, the oblique, the stroke, the solidus, the shilling mark, the division sign, the diagonal, the separatrix, the common slash. It is now also called the ‘forward slash’, particularly when people are reading software aloud since the forward slash needs to be distinguished from the back slash. 

The back slash (also backslash) is itself the victim of multiple naming. It can be called the hack, whack, escape, slosh, backslant, downhill, backwhack, bash, reverse slash, reverse slant, and reversed virgule. The names reflect the usefulness in software programming of a previously rarely used sign. At the same time, the multiple names reflect the fact that programmers invent their languages in isolation. It will take sometime (if ever) for a single name to emerge.

The forward and back slashes are variants of a similar pen stroke, and the vertical slash is a third variant. It too has multiple additional names: the vertical line, verti-bar, vbar, bar, glidus, pipe, polon, stick, and Sheffer stroke. However, the vertical slash is a sign mainly used by mathematicians and logicians, and it does not appear very often in prose.  The back slash is even less common in regular prose, and so it is to the roles of the forward slash that the regular punctuator should give attention.

The names ‘oblique’ and ‘stroke’ identify the slash’s principle role: its use to separate letters, words or numbers to show that they are alternatives, one to another.  A common example is ‘and/or’ in sentences such as: ‘He travels to work by car, bus, bike and/or foot’. The implied meaning is a subtle one since it is saying that the traveller can go to work by any one of the modes named or by any combination of them. 

In the 1970s, at about the time that the oblique began to be called a slash, it began to be found in the formula ‘s/he’, producing statements such as: ‘The officer must report the problem as soon as s/he hears about it.’ That slash operates at first sight as an alternator, but it is also serving to create a gender-neutral, singular, third-person pronoun that English does not possess. An alternative formula is to use ‘they’: ‘The officer must report the problem as soon as they hear about it.’

‘They’ following a singular antecedent is ugly, but so, for many, is the alternator slash itself. It began upsetting people in business and legal documents in the nineteenth century. It continues to upset. In the 1990s, there was a complaint that Foreign Office communications were ‘littered with the oblique stroke or slash entailing constant ambiguity - is it an indolent substitute for "or", or "and", or "I don't know which and can't be bothered to decide between them"?'

Fowler's Dictionary of Modern English Usage has an ‘And/Or’ entry that describes the form as old-fashioned, unaesthetic and ambiguous. Today, Oxford University Press publishes updates of Fowler's Dictionary as edited by Jeremy Butterfield, but Butterfield in 2015 is as grumpy as Fowler in 1925 about the alternator slash. And not only Oxford dislikes the alternator slash, Chicago is equally hostile. Its Manual of Style cautions writers that this ‘Janus-faced term can often be replaced by “and” or “or” with no loss in meaning.’

The slash’s more acceptable roles begin with the solidus. The original solidus was a gold coin that the Romans called a ‘solid’ because it was so heavy and so valuable. They had smaller coins, a twentieth part of the solidus, and those they called ‘denarii’. The twentieth part of a solidus was still a great deal of money so the denarii came to be divided into smaller units, each a 240th part of a solidus and a twelfth part of a denarius.

Those ratios - 1:20; 20:12; 1:12; and 1:240 - will be recognized by anyone who used British coins before 1971. In those pre-decimal days, British money came as pounds, shillings and pence, also known as: ‘LSD’. L, S and D stood for the initial letters of the Latin names of the monetary units: ‘Libra’, ‘solidus’, and ‘denarius’. The pound sign - ‘£’- was formed from the ‘L’ of ‘Libra’. (Today, it is a last vestige of the old currency.) The ‘ʃ’ stood for solidus or shilling; the ‘d’ stood for denarius or penny. The ‘ʃ’ for solidus was the old long ‘s,’ and it was about to be reshaped by the Italians.

In the sixteenth century, European mathematicians were developing the signs and symbols that enable us today to write a formula clearly and swiftly. Before that, a formula had had to be written out in long, tortuous sentences. A start towards a better way had been made with the invention of double-entry booking keeping by the bankers of Florence, and it was not only the English who called a good coin a solidus.  The Italians did so too, and the solidus sign - the ‘ʃ’’ - was adopted to represent fractions in printed texts because printing fractions as one number on top of another is difficult and looks clumsy. A next step with the solidus sign was to remove the now superfluous curls from the long ‘s’. The ‘ʃ’ became the ‘/’. Imported to England, the streamlined solidus became the shilling mark. The phrase ‘twelve shillings and sixpence’ could be printed as 12/6. It was neat, clear, efficient.

The solidus served a useful purpose, and it accumulated numerous roles. It was adopted for marking the line breaks in poems. It came to be a date separator as in 24/10/15 or 10/24/15. (The British order is more logical; the American order is better for date-sorting invoices.) The solidus takes on a specialised bibliographical role when it is used, as the Modern Humanities Research Association urges it should be, as a bilingual title separator: A la recherche du temps perdu/Remembrance of Things Past. The solidus becomes a meta-punctuation mark when proofreaders use it in the margins of texts to separate their proofreaderly comments.

The modern slash evolved from both the ‘virgula’ and the ‘solidus’ – from the twig and the coin. As the solidus, the sign operated at the limits of punctuation. That was not the case when it was used, as it was used by Caxton, as a comma, but, it is the case when, it takes on quasi-mathematical jobs. Its evolving use from the shilling mark to the forward slash has followed a logical progression.


Next Month’s Punctuation Mark: In June, the English Project will tell the story of the Parenthesis.



Adams, Kenneth A., Drafting Without Punctuation? Adams Drafting:, 2015.

Barker, Nicolas, Aldus Manutius and the Development of Greek Script and Type in the Fifteenth Century, Fordham University Press, New York, 1992, pages 111-16.

Bullough, D. A, Alcuin [Albinus, Flaccus] (c.740–804), Abbot of St Martin's, Tours, and Royal Adviser, Oxford Dictionary of National Biography.

Butcher, Janet, Copy-Editing: The Cambridge Handbook, Cambridge University Press, 1993, pages 156-57 and passim.

Butterfield, Jeremy, ed., Fowler's Dictionary of Modern English Usage, Oxford University Press, 2015, pages 49-50, 563.

Cajori, Florian, A History of Mathematical Notations, (2 vols.) The Open Court Publishing Company, Chicago, 1928, page 1: 312.

Chauvier, J. H. A., Treatise on Punctuation, Translated from the French by J. B. Huntington, Simpkin, Marshall & Company, London, 1849, pages 2-3, 17-18, 26, 60.

Cook, Vivian, Frequencies of Punctuation Marks, Punctuation:, Oblique Stroke,

Freedman, Adam, Clause and Effect, New York Times (16 December 2007):

Gibaldi, Joseph, MLA Handbook for Writers of Research Papers, The Modern Language Association, New York, 1999, pages 51-56.

Guberman, Ross, Million Dollar Commas, Legal Writing Pro (2007):

Heyward, Anna, Ugly, Ugly as a Tick on a Dog's Belly, Meanjin (27 December 2014):

Homans, Isaac S., The Coin Book, J. A. Lippincott, Philadelphia 1872, page 3.

Latham, Alison, ed., Oxford Dictionary of Musical Terms, Oxford University Press, 2004, page 40.

Lucas, Bill & Mulvey, Christopher, The History of the English Language in 100 Places, Robert Hale, London, 2013, pages 81-83.

Manguel, Alberto, A History of Reading, Viking, New York, 1996, pages 53-56.

Modern Humanities Research Association, The MHRA Style Guide, Modern Humanities Research Association, London, 2002, page 57.

Norris, Mary, Holy Writ: Learning to Love the House style, Extract from  Confessions of a Comma Queen, The New Yorker (23 February 2015):

Norris, Mary, Quotes, Good Reads:

Norris, Mary, Between You & Me: Confessions of a Comma Queen, W.W. Norton & Company, New York, 2015. 

Oxford University Press, New Hart’s Rules: The Handbook of Style for Writers and Editors, Oxford University Press, 2005, pages 67-72, 72-73, 83-84, 125.

Parkes, Malcolm Beckwith, Pause and Effect: An Introduction to the History of Punctuation in the West, Ashgate, Farnham, 1992, pages 4, 30, 36, 49, 51.

Revolvy, Backslash, Revolvy:

RIPE Network Coordination Centre, Understanding IP Addressing, Ripe (20 April 2014):

Saenger, Paul, Space Between Words: The Origins of Silent Reading, Stanford University Press, 2000, pages 16-17, 24.

Spears, Richard A., McGraw-Hill's Dictionary of American Slang and Colloquial Expressions, McGraw-Hill, New York, 2005.

Stein, Gertrude, Punctuation In Prose,  About Education: Stein’s lecture was first published in Lectures in America (Random House, New York),1935.

University of Chicago Press Staff, The Chicago Manual of Style, University of Chicago Press, 2010, pages 311-24, 200.