Q What exactly is the difference between the words “disinterested” and “uninterested”? – R.B., Minneapolis, Minn.

A: According to some pundits, “disinterested” should only be used in an ethical sense meaning “unbiased,” while “uninterested” should mean “not interested.” In other words, the referee at the basketball game is ideally a disinterested official, while your 5-year-old who cares nothing for the game and only wants to play on the bleachers is uninterested.

As you might imagine, this distinction is not reflected consistently in actual usage. In fact, “disinterested” is often used to mean “not interested,” despite the criticism of this use. Some people claim that the ethical sense of “disinterested” is its original meaning, and that this meaning is now falling into disuse because of the prevalence of the “not interested” sense.

Neither of these assertions is true. The simple negative use, “not interested,” was the first meaning of “disinterested,” dating from before 1612. (Curiously, the earliest senses of “uninterested” were in the ethical vein – of the same kind now claimed as the correct meaning of “disinterested.” “Uninterested” no longer carries any ethical meaning, however.) What’s more, our evidence shows that the ethical sense of “disinterested” is not fading at all – it accounts for about 70 percent of the word’s use in published writing.

The ethical sense of “disinterested” is applied to human subjects – such as the referee above – and to nonhuman ones, as in “disinterested intellectual curiosity.” The simple negative sense is usually applied to human subjects. About half the time it is used in the phrase “disinterested in,” a construction not used for the ethical sense. “Disinterested” also carries a third sense, along the same lines as the simple negative one, but slightly more emphatic, meaning “having lost interest.” An example would be “He grew disinterested in his job.”

“Uninterested,” of course, continues to be used as well, and many writers and editors do observe the distinction promoted by usage commentators. Those same writers and editors will doubtless continue to regard the use of “disinterested” to mean “not interested” as an error. There is no question that this use is established in current English, but if you want to be absolutely sure of avoiding criticism, you should steer clear of it.

Q I remember once seeing a list of amusing terms for groups of animals. My kids got such a kick out of them. The only ones I can remember are “a gaggle of geese” and, of course, “a school of fish.” Can you refresh my memory with others? – A.G., New Haven, Conn.

A: Animal groups often have appealing names that conjure up images of our furry or feathered friends in action. Some of the names we will share are, despite their appeal, used infrequently, but others are quite common.

Some group terms can be correctly applied to many animals but tend to be used in connection with a certain species. Among these are “pod,” usually used to describe a group of whales or seals; “gang,” as in “a gang of elk”; “drift” as in “a drift of hogs”; and “kindle,” as in “a kindle of kittens.” Giraffes and kangaroos, among others, come in “troops.” We also have evidence of the chiefly Australian use of “mob” in “a mob of kangaroos.”

As you suggest, children are often delighted by the names of animal groups, especially those that are somehow descriptive. In this category we find “a pride of lions,” “a sloth of bears,” “a skulk of foxes” and “a crash of rhinoceroses.”

Birds seem to be particularly amenable to the application of imaginative collective terms, and some of these are very old, if never very common. As evidence of this we have “a charm of finches,” “a murmuration of starlings,” and “a murder of crows.” A flock of peacocks is aptly named a “muster,” a word that once had the meaning of “a display or presentation.” Additionally, a “covey” is usually a flock of partridges, a “rafter” usually means a flock of turkeys, and a “bevy” usually means a flock of quail.

Q What can you tell me about the odd term “incunabulum”? – C.K., Des Moines, Iowa

A: “Incunabulum” is indeed an odd term with a rather technical meaning: “a book printed before 1501.” The word is derived from the Latin plural noun “incunabula,” which means literally “bands used to hold a baby in a cradle” and which also was used figuratively to mean “childhood” or “beginning.”

“Incunabulum,” then, can be understood as referring to a book that was produced when printing was in its infancy. The year 1501 is actually an arbitrary date; the earliest period of printing, during which the field was something of a highly competitive free-for-all, ran well into the 16th century. It wasn’t until after around 1550 that printing began to be regulated from within and controlled from without. The word “incunabulum” in its current sense was first recorded in the middle of the 19th century.

The number of incunabula produced by the 15th-century European presses is generally considered to be about 35,000 or more, to which should be added a considerable percentage of texts that did survive the test of time intact, such as single sheets, cheap romances, ballads and devotional tracts.

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.