Q: Sir Ernest Gowers has written that the main reason for the popularity of Henry W. Fowler’s A Dictionary of Modern English Usage is “the idiosyncrasy of the author.” My understanding is that “idiosyncrasy” is a quirk of personality, not personality as a whole.
A: Etymologically, “idiosyncrasy” refers to an individual’s overall makeup—a combination of physical and mental characteristics. However, it now usually means a peculiar trait of someone or, less commonly, something.
The etymological sense reflects the Greek origin of the usage. In Hellenistic Greek, spoken from roughly 300 BC to AD 300, the noun ἰδιοσυγκρασία (idiosugkrasia) meant an individual’s combination of personality, appearance, character, and so on.
As John Ayto explains in his Dictionary of Word Origins, the usage comes from two ancient Greek terms: ἴδιος (idios), “one’s own,” and σύγκρασις (sugkrasis), “mixture.” (In Hellenistic Greek, σύγκρασις is a mixture of personal characteristics.)
Fowler favored the etymological sense of “idiosyncrasy.” In the 1926 first edition of Modern English Usage, he says “idiosyncrasy” should refer to overall character, not a single trait, and he defended its spelling with an “s” (not a “c”) at the end to reflect its etymology.
Gowers has a similar entry in his 1965 second edition of Fowler’s usage guide. The comment that got your attention is in the preface.
The last two editors of the usage guide, Robert Burchfield and Jeremy Butterworth, agree with Fowler on the spelling but don’t restrict the modern meaning to ancient etymology.
As Burchfield puts it in the 1996 third edition and Butterfield repeats in the 2015 fourth, “It is not suggested that everyone should be a walking etymologist, but simply that people should learn to spell correctly.”
All ten standard dictionaries we regularly consult define “idiosyncrasy” as an unusual characteristic or behavior of someone or something. However, four of them include the less common sense favored by Fowler: the overall makeup of a person or thing.
We’d add that the plural “idiosyncrasies” is often used in phrases describing idiosyncratic people or things (“his many idiosyncrasies,” “her iPad’s little idiosyncrasies”).
In fact Lexico, an online standard dictionary with content from Oxford University Press, says the term is “usually idiosyncrasies” when referring to “a mode of behavior or way of thought peculiar to an individual.”
The Oxford English Dictionary, an etymological dictionary, says English adopted “idiosyncrasy” in the early 17th century, either directly from Hellenistic Greek or by way of idiosyncrasie, which showed up in French in 1581.
In English, the word originally meant “peculiarity of physical or physiological constitution” or “an instance of this,” the OED says. The dictionary’s earliest citation is from a medical treatise warning about the use of arsenic amulets to ward off plague:
“The idiosygcrasye or particular Natures (as Galen calleth them) are vnknown” (A Modest Defence of the Caueat Giuen [Caveat Given] to the Wearers of Impoisoned Amulets, as Preseruatiues [Protectives] From the Plague, 1604, by the English physician Francis Herring).
A few decades later, the term took on the sense Fowler preferred, which the OED defines as “the individuality of a person’s outlook, temperament, or behaviour; the distinctive nature of something.”
The first Oxford example is from a dictionary of English words derived from other languages: “Idiosyncrasie, the proper, or natural temper of any thing” (The New World of English Words, 1658, by Edward Phillips).
The term soon took on the usual modern sense, which the OED defines as “a way of thinking or a mode of behaviour limited to a particular person, people, or type of person.” The dictionary’s earliest citation, which we’ve expanded, is from a treatise attacking dogmatism:
“And I believe the Understanding has its Idiosyncrasies, as well as other faculties. Some men are made to superstition, others to frantick Enthusiasm; the former by the cold of a timorous heart, the latter by the heat of a temerarious brain: And there are natures, as fatally averse to either.” (The Vanity of Dogmatizing, 1661, by the English philosopher and clergyman Joseph Glanvill.)
We’ll end with the latest Oxford citation for this sense: “One idiosyncrasy of the tequila drinker is the desire to swill the last mouthful in the bottle and with it the Agave worm” (from The Mammoth Book of Cocktails, 2003, by Paul Martin).