Wordorigins.org

A round robin is a type of sports tournament where all the players play one another in succession. This sense comes from an older, nautical jargon term referring to a document signed by mutineers. In a round robin document, the mutineers would sign their names in a circle, so the authorities could not identify the first to sign, who presumably would be the ring leaders. (Despite the temptation to connect round robin and ringleader, the two words are etymologically unconnected.) Some sources suggest that this usage of round robin comes from the French rond ruban, or round ribbon, that was tied around these petitions--but little evidence exists to support this guess. From the Weekly Journal of 3 January 1730:

A Round Robin is a Name given by Seamen, to an Instrument on which they sign their Names round a Circle, to prevent the Ring-leader being discover’d by it, if found.

The origin of the name of this Jamaican musical style is unknown. Credit for coining the word goes to Toots Hibbert for his 1968 song Do the Reggay. Some suggest it comes from the Jamaican English rege-rege meaning quarrel or row. Others indicate that it is from raggedy a reference to a quality of the musical style.

From an advertisement in the 7 September 1968 Daily Gleaner of Kingston, Jamaica:

Come do this brand new dance THE REGGAE.

(Source: Oxford English Dictionary, 2nd Edition; Newspaperarchive.com)

To rain cats and dogs is to rain very heavily. The metaphor behind the phrase is that of a dog and a cat fighting, something noisy and violent. The metaphor of a storm resembling a dog and cat fight dates to the mid-17th century, although the phrase, as we know it today, doesn’t appear for another half century. Henry Vaughn’s Olor Iscanus of 1651 goes:

The Pedlars of our age have business yet,
And gladly would against the Fayr-day fit
Themselves with such a Roofe, that can secure
Their Wares from Dogs and Cats rain’d in showre

Pussyfoot, which means a delicate, soft step comes from the imagery of a cat’s careful tread. To pussyfoot is to proceed with caution, subtlety, and delicacy and is used pejoratively. The term is American in origin and, in adjectival form, dates to at least 1893. From Scribner’s Magazine of November of that year:

Men who were beginning to walk pussy-footed and shy at shadows.¹

This is an aviation term. It means to fly an aircraft beyond the limits it was designed for, especially in the context of flight testing. Envelope has several secondary definitions in mathematical and engineering jargon referring to the area covered by a series of curves. So in the world of aeronautical engineering the envelope is the collection of curves that describe the maximum performance of an aircraft. To push the envelope is to take the aircraft to the edge of what it was designed to do and try and take it beyond.

The mathematical sense of envelope dates to the 19th century. Isaac Todhunter’s 1871 Differential Calculus:

The locus of the ultimate intersections of a series of curves is called the envelop [sic] of the series of curves.

To pull the wool over someone’s eyes is to deceive them. The metaphor behind this phrase is quite straightforward, but not readily apparent today. The wool refers to a powdered wig. To pull the wool down over a man’s eyes is to temporarily blind him. The phrase is an Americanism and variants include the use of the verbs to draw and to spread, in addition to pull. From the Jamestown Journal (N.Y.) of 24 April 1839:

That lawyer has been trying to spread the wool over your eyes.

(Source: Oxford English Dictionary, 2nd Edition)

The pros from Dover is an American slang term for outside consultants who are brought into a business to troubleshoot and solve problems. The phrase comes from the 1968 book M*A*S*H by Richard Hooker. In the book, the character Hawkeye is described as using the guise of being the pro from Dover to obtain free entrance to golf courses:

[Hawkeye] would walk confidently into a pro shop, smile, comment upon the nice condition of the course, explain that he was just passing through and that he was Joe, Dave or Jack Somebody, the pro from Dover. This resulted, about eight times out of ten, in an invitation to play for free. If forced into conversation, he became the pro from Dover, New Hampshire, Massachusetts, New Jersey, England, Ohio, Delaware, Tennessee, or Dover-Foxcroft, Maine, whichever seemed safest.

Later on in the book, when Hawkeye and fellow surgeon Trapper are called from Korea to Tokyo to perform surgery on a congressman’s son, the following exchange takes place:

“All right,” Trapper said. “Somebody trot out the latest pictures of this kid with the shell fragment in his chest.”
No one moved.
“Snap it up!” yelled Hawkeye. “We’re the pros from Dover, and the last pictures we saw must be forty-eight hours old by now.”

This latter exchange is repeated in the 1970 movie, but the term pros from Dover is not explained in the script. People who had seen the movie, but not read the book, started using the phrase to mean outside experts/consultants without understanding that Hawkeye was using the term facetiously, referring to an old con he used to run.

(Sources: M*A*S*H, by Richard Hooker; M*A*S*H (film), 20th Century Fox, 1970.)

The the expressions go pound sand and not enough sense to pound sand are American slang from the 19th century. It is a reference menial, and often pointless, labor. From Alexander Smith’s 1857 City Poems:

Peopled now By outcasts, sullen men, bold girls who sat Pounding sand in the sun.

And we have this from the 26 December 1877 Globe of Atchison, Kansas:

We don’t know whether the young man you refer to knows enough to pound sand or not.

The latter phrase often appears in a longer form, not enough sense to pound sand down a rathole. This appears somewhat later. From the 1912 Dialect Notes:

He wouldn’t know enough to pound sand in a rat-hole; so don’t get him.

(Source: Oxford English Dictionary, 2nd & 3rd Editions)

A pot-boiler is a book or other work of art produced for the express purpose of making money, rather than for any artistic merit. The imagery behind the term is of providing food for the pot or table. The term dates to the late 18th century. From painter James Barry’s 1783 An Account of a Series of Pictures:

Some others...in great measure compensate for the heaps of inconsequential trash, or pot-boilers (as they are called) which are obtruded upon the public view.

The use of the imagery of keeping food on the stove is even older. Potboiling is found in use as early as 1775 meaning to provide for life’s necessities. From Samuel J. Pratt’s 1775 Liberal Opinions:

Send I say the 1l. 1s. just for the pot-boiling business, and who knows what tomorrow may bring forth.

And there is this from Peter Heylin’s 1661 Ecclesia Restavrata:

So poor, that it is hardly able to keep the Pot boiling for a Parsons Dinner.

(Source: Oxford English Dictionary, 3rd Edition)

When something is posh it is luxurious, stylish, pretentious, one of the good things in life associated with wealth and high social status. Its origin is not known for certain, but the best guess is that it comes from a 19th century slang term for money that in turn is taken from a Romani (Gypsy) word.

That Romani word is påš, meaning half. It’s used in various forms like the Welsh Romani påš xåra, or half-penny, or the Angloromani posh-hórri. The English slang use of posh to mean money appears as early as 1830 in the records of court proceedings. From the Sessions Papers of the Old Bailey from that year:

He had not got the posh (which means money) yet.