$ is the combination of U and S- making the US the only country with its name in its currency symbol.
it was used in early government bonds, later the bottom part of the U was cut off, and in the 20th cent ppl combined the lines.

# is a pound sign- it derived from the abbreviation lb for the word libra which means pound in latin and spanish. typesetters used a special character for it â„” which is still available in our computer fonts, then it was simplified for shorthand writing.

It is true that the Latin word “io” is an interjection, although it can mean pain as well as joy:

IO, interj., expressing joy, “ho! huzza! hurra!” [references from Plautus, Horace, and Pliny]–II. Expressing pain. “oh! ah!” [references from Plautus and Tibullus]–III. Used in a sudden and vehement call, “holla! look! quick!” [references from Vergil and Ovid]. (Lewis & Short, A Latin Dictionary, 1879, pp.997-998)

I can find no evidence, however, for it being used as an abbreviation, and the reference sources I’ve checked (Encyclopedia Britannica Online: “Punctuation in Greek and Latin to 1600;” Concise Oxford Companion to the English Language: “Punctuation”) give no such origin story. What they do say is that the exclamation point wasn’t introduced into the punctuation pantheon until the 17th century and, as a student of medieval Latin palaeography, I can tell you that it makes no sense to have introduced abbreviations at a time when print had already taken over from handwritten manuscripts (the reason for the development of palaeographical abbreviations in the first place).

I find the source–Uncle John–to be incredibly suspect. Their origin story for the question mark, for example–Latin scholars most emphatically did NOT end query sentences with the word “qu[a]estio”–there was no need, as the query words were already built into the sentence. According to Cappelli’s “Dizionario di abbreviature latine ed italiane,” the definitive work on Latin abbreviations, “qu[a]estio” was originally abbreviated with “qtio” with a line over it. In the 15th century, “qo” with an arched line over it was introduced, but it would never have been placed at the end of a sentence.

According to the “Concise Oxford Companion to the English Language,” “The term QUESTION MARK has been used for less than a century: the earlier term was mark/point of interrogation (late 16c). It is a descendant of the punctus interrogativus, one of the marks found in 10–13c liturgical manuscripts, where it indicated inflection of the voice. The terms mark/note of exclamation and SEMICOLON both date from the 17c.”

I’m sorry to be such a pedant about this–and I’m happy to do further research into the orthography of the exclamation point–but this sort of folk etymology is a particular pet peeve of mine (I’m constantly debunking the email forwards I get from my mother, which purport to describe the origins of folk phrases), and I wanted to set the record a little straughter.

I fear that one must always be a little suspicious of historical data that comes from a book called Uncle John’s Supremely Satisfying Bathroom Reader. For a popular, readable, yet eminently accurate version of this kind of book, I highly recommend Brewer’s Dictionary of Phrase and Fable, which should be in every thinking person’s library!

All the best,

Karen

p.s.–Uncle John also makes reference, in the entry on the ampersand, to the “Roman scribe Marcus Tullius Tiro.” Marcus Tullius Cicero, the orator and rhetor, did have a Greek slave named, simply, Tiro who acted as his scribe, and who invented a series of abbreviations that are known as “Tironian notes.” He did not invent the ampersand, however. Tiro’s abbreviation for “et” looked like a 7 (which is why I’ve always found a particular delight on the joining of the & and 7 on the same keyboard key). The use of the Tironian 7 as “et” continued well into the middle ages, and the introduction of the ampersand, which really is a contorted rendering of the actual word “et,” dates to around the 12th century. According to the OED, the etymology of the word “ampersand” is “Corruption of ‘and per se-and’, the old way of spelling and naming the character & ; i.e. ‘& by itself = and;’ found in various forms in almost all the dialect Glossaries.” This has nothing to do with the alphabet story offered via Uncle John.

Also, the interrobang is a punctuation mark whose time, I think, has come: http://en.wikipedia.org/wiki/Interrobang

Here’s a good-as-any discussion of the word’s uncertain and contested origin:
http://www.worldwidewords.org/weirdwords/ww-oct1.htm

I’m probably wrong though…

today:
yo! wassup!