Last week's addendum was Duvet Days. It triggered a similar alliteration, Dog Days. I had no idea it came from the classical world. I'm really not gloating, but I'll be spending most of them in Maine.
The phrase Dog Days or "the dog days of summer", Latin: Caniculae, Caniculares dies, refers to the hottest, most sultry days of summer. In the northern hemisphere they usually fall between early July and early September whilst in the Southern hemisphere they are usually between January and early March. The actual dates vary greatly from region to region, depending on latitude and climate. Dog Days can also define a time period or event that is very hot or stagnant, or marked by dull lack of progress.
The term "Dog Days" was used by the Greeks (see, e.g., Aristotle's Physics, 199a2), as well as the ancient Romans (who called these days caniculares dies (days of the dogs)) after Sirius (the "Dog Star", in Latin Canicula), the brightest star in the heavens besides the Sun. The dog days of summer are also called canicular days.
The Dog Days originally were the days when Sirius, the Dog Star, rose just before or at the same time as sunrise (heliacal rising), which is no longer true, owing to precession of the equinoxes. The ancients sacrificed a brown dog at the beginning of the Dog Days to appease the rage of Sirius, believing that the star was the cause of the hot, sultry weather.
Dog Days were popularly believed to be an evil time "when the seas boiled, wine turned sour, dogs grew mad, and all creatures became languid, causing to man burning fevers, hysterics, and phrensies" according to Brady's Clavis Calendarium, 1813 ....
In recent years, the phrase "Dog Days" or "Dog Days of Summer" have also found new meanings. The term has frequently been used in reference to the American stock market(s). Typically, summer is a very slow time for the stock market, and additionally, poorly performing stocks with little future potential are frequently known as "dogs."
A casual survey will usually find that many people believe the phrase is in reference to the conspicuous laziness of domesticated dogs (who are in danger of overheating with too much exercise) during the hottest days of the summer. When speaking of "Dog Days" there seems to be a connotation of lying or "dogging" around, or being "dog tired" on these hot and humid days. Although these meanings have nothing to do with the original source of the phrase, they may have been attached to the phrase in recent years due to common usage or misunderstanding of the origin of the phrase.