Q: Why is “d” silent before “j” in words like “adjective,” “adjust,” and “adjunct”? Is this an issue of phonology, or is it related to the etymology of these words and their Latin prefix?
A: The “d” isn’t silent in these words. It’s built into the letter “j” as pronounced in modern English. This “j” sound is rendered in phonetic symbols as /dʒ/.
In modern French, you may have noticed, the letter “j” is sounded by /ʒ/ alone—as in je and jeune—a sound similar to the one we hear in the middle of our word “vision.”
But in English, “j” is much stronger—as in “jury” and “banjo”—incorporating a touch of “d” at the beginning. This is why the English consonant is represented by the more complex symbol /dʒ/, reflecting both sounds.
We can’t say for sure why those words you mention kept the “d” in their spellings. Certainly they would be pronounced just the same without it. But your suggestion may be correct, and perhaps the “d” was retained for etymological reasons.
The “d” got there in the first place because all English words beginning with “adj-” are ultimately derived from Latin words prefixed with ad-. Such words include “adjacent,” “adjective,” “adjoin,” “adjourn,” “adjudicate,” “adjunct,” “adjure,” “adjust,” and “adjutant.”
The Latin prefix can denote motion “to,” “toward,” “near,” or “at,” and it can indicate “change into, addition, adherence, increase, or intensification,” according to the Oxford English Dictionary.
Taking “adjective” as an example, it can be traced to the Latin ad– plus iacere (to lay, to throw). When it first came into English in the 14th century, it was spelled “adiectif” because English had not yet adopted the letter “j.”
Similarly, other “adj-” words that date from the Middle English period originally had no “j.” For instance, “adjacent” was spelled “adiacent”; “adjoin” was sometimes “adioyne” (among many other spellings); “adjourn” was “adiurne”; “adjunct” was “adiuncte”; and “adjure” was “adiure.”
Even later words like “adjutant” and “adjust,” which came along in the early 1600s, originally had two spellings, sometimes with “j” and sometimes with “i” (“adiutant,” “adiust”).
But even when spelled with “i,” such words were pronounced as if the letter were a modern “j.”
As the OED explains within its entry for the letter “j,” French spellings brought into English with the Norman Conquest introduced the Old French use of “i” as a consonant pronounced /dʒ/. This, the dictionary says, is the “sound which English has ever since retained in words derived from that source, although in French itself the sound was subsequently, by loss of its first element, simplified to /ʒ/.”
For a time, the double identity of “i” resulted in some confusion, because, as Oxford says, the letter “represented at once the vowel sound of i, and a consonant sound /dʒ/, far removed from the vowel.”
It wasn’t until the 17th century that “i” was consistently used for the vowel and “j” for the consonant.
In case you’re interested, we’ve mentioned the development of “j” in other posts, including one in 2013 about the name “Jesus.”
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