Why Is ‘No.’ Short for “Number”?

In most cases, no usually means, well “no.” But the combination of n and o can also refer to something else: “number.” You’ll see it everywhere from media talking about a song that’s a No. 1 hit to a No. 1 pencil. But how did these two letters come to be short for “number?” 

1. The Origins of #
2. It All Goes Back to Latin
3. The Complex World of Latin Scribal Abbreviations

The Origins of #

Along with simple shortenings such as n. or num., one of the more curious methods is the number sign or hash symbol, #. 

It’s a symbol you’ll see everywhere from room and apartment numbers (“Flat #15”) to high school test papers (“Question #3”), and even on the keypad of your telephone. Historically, it’s thought to be derived from a combination of the letters l and b (representing a “pound weight,” or libro pondo in Latin) that were later joined together as a single symbol using a connecting horizontal stroke: ℔. 

And as that symbol gradually simplified and merged together over time, our familiar “hash” symbol—or literally, our “hatched” symbol—began to emerge, used more loosely alongside any number or numbers, not just weights and measures. 

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It All Goes Back to Latin

Another curious method of representing the word number, however, is “No.” After all, number itself doesn’t contain a letter o, so why use one here? Just like the hash symbol before it, “No.” likewise has its root not in English, but in Latin. 

The Latin word for “number” (from which our own word number is also descended) was numerus. Latin was riddled with multiple grammatical cases and tenses far beyond those we use in English today, including the so-called ablative case that was used in contexts relating to things like location, association, and separation; a common bitesize explanation of how the ablative was used in Latin is that it roughly corresponds to contexts where we would use a from, with, in, or by in English today. And the Latin ablative form of the word numerus was numero—essentially, “in number.” 

So when you see number shortened to “No.” in English, you’re not actually seeing an English abbreviation at all, but a Latin one. But why N-O? Why not N-U, or even just N?

In English, we’re used to taking the first letter (or first few letters) of words of syllables to form abbreviations. Taking the first and last letter of the word we want to shorten, ultimately, seems like a bit of a strange method in comparison. The reason why numero became “No.” however, also neatly explains why you might also occasionally see “No.” cut down to a single, often rather stylized character or ligature, with the O slightly raised above the midpoint of the line: №. 

The Complex World of Latin Scribal Abbreviations

The origins of this particular form of “No.” take us from the complicated world of Latin grammar, into the even more complicated world of Latin scribal abbreviations. Long before fast, neat, typewritten text came along, medieval scribes would be employed to note down or reproduce all important documents and records by hand. 

That understandably was a rather time-consuming task—but add to it the equally time-consuming processes often involved in making ink, as well as the relative expense of writing supplies like vellum and parchment, and any method that sped up or economized handing in medieval times was understandably an advantage. As a result, a vast system of standardized abbreviations gradually emerged that allowed scribes to shorten many of the longer or more frequently used words in their handwritten texts, and thereby save precious time and resources. 

The full system of Latin scribal abbreviations or sigla—comprising a rich mixture of symbols, dots, strokes, swirls, and all manner of other handwritten shapes and strokes—is so extraordinarily complex that entire books and entire fields of study have been dedicated to it. But at least one of the techniques that these scribes employed was to slightly elevate the final letter of an abbreviated word in their writing, with the resulting so-called “superscript” character indicating where the word in question ended. 

The word numero, ultimately, came to be shortened to “№” with a raised letter o, which (rather like the pound symbol before it) gradually came to be considered a single ligature. Although now rare, this symbol has remained in occasional use ever since and is typically included as an optional character even in some contemporary typefaces. The use of “No.” as an abbreviation of number (or rather numero), however, remains as common and as familiar as always.