Q A phrase I often see is “under the aegis of” something or other, and I’m interested in finding our more about it. What does it mean? Where does it come from? – M.D., Harrisburg, Pa.

A: Today when we speak of something as being “under the aegis of” we generally mean that it is under the authority, sponsorship or control of another. In a way, then, the thing that is in the subordinate position is being protected by the other; hence an aegis is something that protects or shields.

In ancient Greece the word “aigis” (which became “aegis” in Latin) was used literally of something that offered physical protection.

In Greek mythology, the aegis in one sense was a thundercloud, housing the thunderbolts that Zeus wielded as his signature weapon.

In what was probably the original sense, the aegis was a cloak or mantle made of goatskin taken from the she-goat who had suckled Zeus as a babe (in Greek, “aigis” means literally “goatskin”). In this incarnation, it was part of Zeus’s protective armor in his war against the Titans.

In yet another tradition, the aegis was an impregnable, shield-like weapon that was made by the metalworking god Hephaestus to resemble a thundercloud and that was fringed with tassels suggestive of thunderbolts.

Zeus occasionally entrusted the aegis to other gods and especially Athena, of whom the aegis later became an attribute. In the myths centering on Athena, the aegis became a goatskin mantle bearing the likeness of the Gorgon Medusa and fringed with serpents. In artistic representations Athena is shown wearing the aegis as a sort of protective coat over her chest, or draping the leather cloak over her arm and using it as a shield to ward off blows. The aegis became an attribute of the goddess’s divine protection and power.

The aegis became a familiar classical reference in English literature, and by the 18th century “aegis” was being used figuratively for any kind of seemingly impregnable shield. In current use, the sense of the word equivalent to “auspices” has become dominant.

Q What are the differences between the verbs “founder” and “flounder”? I find that I often get these two words confused. – S.F., Willimantic, Conn.

A: You aren’t the only person with this problem. Some usage commentators have noted that the two words are often mistaken for one another in edited writing.

Perhaps the fact the English language has a lot of words starting with “f” that suggest error or failure, such as “flunk,” “fold,” “fizzle,” “flop” and “fail” itself, contributes to that confusion. Although “founder” and “flounder” have distinct literal senses, they are often conflated when used figuratively.

A ship that founders is one that fills with water and sinks. The word can also be used to mean “break down, collapse, or fail,” as in, “The business lost money and foundered.”

A person who flounders is struggling to move or thrashing about trying to gain footing.

It might make you think of a fish that is flapping around out of water, since “flounder,” when used as a noun, refers to a type of fish. Naturally, “flounder” can also be used figuratively to mean “to act clumsily or ineffectually,” as in, “He floundered in his efforts to impress the girl.”

Q I came across a strange word: “shunpike.” What does “shunpike” mean, and where does it come from? – N.P., Tampa, Fla.

A: You may have used a “shunpike,” perhaps on a holiday weekend, without even realizing it.

A “shunpike” is a side road used to avoid the toll (or the speed and traffic) on a highway – in other words, a road that is used to “shun” the turnpike.

America’s love affair with the automobile and the development of a national system of superhighways (along with the occasional desire to seek out paths less traveled) is a story that dates from the 20th century.

So the word “shunpike,” too, must be a 20th-century phenomenon, right? No. Toll roads have actually existed since the days of the horse and buggy (the word “turnpike,” which originally meant “tollgate,” dates from the 16th century). In fact, toll roads were quite common in 19th-century America, and “shunpike” was coined in the middle of that century, almost half a century before the first Model T rolled out of the factory.

This column was prepared by the editors of Merriam-Webster’s Collegiate Dictionary, Tenth Edition. Readers may send questions to Merriam-Webster’s Wordwatch, P.O. Box 281, 47 Federal St., Springfield, MA 01102.