The '#' symbol has many names, but hash is the one that confuses me. I know the etymology of the word 'hash', but how did it become associated with that character?

  • # is used in Perl for comments. So does Python and many others. C++ uses either // for lines or /*this is a comment*/ for blocks. Nothing to do with question, just saying.
    – Zebrafish
    Commented Mar 24, 2018 at 1:33
  • 1
    The octothorpe ("#" character) is commonly referred to as "hash".
    – Hot Licks
    Commented Mar 24, 2018 at 1:33
  • (I'll note that there are very few programming languages that speak, so I can't vouch for what they may call it.)
    – Hot Licks
    Commented Mar 24, 2018 at 1:34
  • 1
    @Hot Licks My code tells me to burn things. Seriously, is this such a bad question? I'm curious also.
    – Zebrafish
    Commented Mar 24, 2018 at 1:36
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    @Zebrafish In C and C++ the "#" character is used for preprocessor directives. However, in C# the "#" character is not used. In fact the "#" in the name is used in place of the musical sharp character since so few people want to enter the Unicode for that---including Anders Hejlsberg who co-invented the language.
    – m_a_s
    Commented Mar 24, 2018 at 3:24

2 Answers 2


So my understanding is that you want to know how this # symbol came to be given the word "hash".

The word "hash" is derived from the French "hache".

hache, from Old French, past participle of hacher, hachier, to chop up, from hache, axe, of Germanic origin; see hatchet
American Heritage Dictionary

So how does the # sign relate to cutting or chopping up?

Hatching (hachure in French) is an artistic technique used to create tonal or shading effects by drawing (or painting or scribing) closely spaced parallel lines.
Hatching Wikipedia article

Example of hatching:

etching of a child's face using the hatching technique


There's a resemblance between this artistic technique and #, that's my guess anyway.

Additional info:

In the United Kingdom and Ireland, it is generally called a hash (probably ultimately from "hatch", referring to cross-hatching, although the exact derivation is disputed).
Origin and Names of Hash Sign, Wikipedia

"cross-hatching" here meaning the art technique I mentioned before.

Furthermore, from a blog:

Several online sources claim that hash came from "hatch", as in the cross hatching artists use when drawing. Except, the only place I find this is in these claims. They cite no additional sources, and I have found no additional sources. I've only seen this as a just-so story presented to fill that vacuum.

And to confuse things, from that same blog, is found this from a google search:

enter image description here

So there's also the possibility that it's so named because the older version used to look like an 'H'.

Furthermore the hash sign Wikipedia article says that the '#' symbol could come from a symbol originally looking like this ℔ meaning some type of pound measure, and that over time:

Ultimately, the symbol was reduced for clarity as an overlay of two horizontal strokes "=" across two slash-like strokes "//".

The original source for this claim is the book: The Ancient Roots of Punctuation

So there you go, many explanations at odds with each other. You really opened a can.

  • "You really opened a can." ---> Yeah, I could sort of tell just from what came up when I was googling it....are we, like, breaking fresh ground here in etymological archaeology? Are there no definitive sources on this? Good answer though. Commented Mar 24, 2018 at 7:35
  • @Aerovistae I doubt mere mortals like us are breaking any ground. Any idea you have is likely to have been had by someone else, there are 7.5 billion people in the world and over 100 billion people who have lived. This makes me feel small. Sorry drag down the mood.
    – Zebrafish
    Commented Mar 24, 2018 at 7:51
  • @Aerovistae - The relationship of the symbol "hash" to chopped-up meat is something that's intuitively obvious to even tech-illiterate folks. You never see it explained because it hasn't needed explaining.
    – Hot Licks
    Commented Mar 24, 2018 at 12:15
  • @Mari-LouA I distinctly remember the OP mentioning they knew that hash was etymologically derived from French hache. I can't find it in the comments so it's possible it was deleted or edited out of the comment. Pretty sure I didn't dream it up.
    – Zebrafish
    Commented Mar 24, 2018 at 13:16
  • @Mari-LouA Also there was another answer which addressed the origin of hash with respect to social media hashtags. I assume that question was deleted once the OP made it clear what they were asking. That's when I wrote my answer. Though, it doesn't seem so clear anymore, as I said, I'm not sure if it was a deleted or edited comment.
    – Zebrafish
    Commented Mar 24, 2018 at 13:18

This is hash (of the non-drug kind):

skillet potato and meat hash

The first step in the preparation of hash is to slice the component meats and vegetables into small cubes, often accomplished by simply slicing one direction, then the other, kind of like this:

hashtag symbol

This slicing action (literal or figurative) is often referred to as "making a hash".

This figurative sense can be seen in this quote from 1798:

they were, in reality, nothing but a crude hash of tyranny and licentiousness

But note that the term "hash" or "hash mark" has been used for a century, at least, to refer to stripes on military uniforms, to markings on a sports field, or to the marks on the traditional jailhouse calendar:

 a sequence of four vertical lines struck through

The term may also be used by, e.g, a carpenter to refer to a pencil mark on a board.

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