Q: I’ve come across a cartoon online that raises a good question: If “tomb” is pronounced TOOM and “womb” is pronounced WOOM,” why isn’t “bomb” pronounced BOOM?

A: In the past, “bomb” was sometimes spelled “boom” and probably pronounced that way too. In fact, a “bomb” was originally a “boom,” etymologically speaking.

The two words have the same ancestor, the Latin bombus (a booming, buzzing, or humming sound). The Romans got the word from the Greek βόμβος (bómbos, a deep hollow sound), which was “probably imitative in origin,” according to the Chambers Dictionary of Etymology.

The Latin noun produced the words for “bomb” in Italian and Spanish (bomba), French (bombe), and finally English, where it first appeared in the late 1500s as “bome,” without the final “b.”

The “bome” spelling was a translation of the Spanish term. It was first recorded in Robert Parke’s 1588 English version of a history of China written by Juan González de Mendoza. Here’s the OED citation:

“They vse … in their wars … many bomes of fire, full of olde iron, and arrowes made with powder & fire worke, with the which they do much harme and destroy their enimies.”

After that, however, the word disappeared for almost a century, reappearing as a borrowing of the French bombe, complete with the “b” and “e” at the end.

The earliest English example we’ve found is from A Treatise of the Arms and Engines of War, a 1678 English translation of a French book on war by Louis de Gaya. A section entitled “Of Bombes” begins:

“Bombes are of a late Invention. … They are made all of Iron, and are hollow … they are filled with Fire-works and Powder, and then are stopped with a Bung or Stopple well closed; in the middle of which is left a hole to apply the Fuse to.”

The Oxford English Dictionary’s earliest “bombe” example appeared a few years later: “They shoot their Bombes near two Miles, and they weigh 250 English Pounds a piece” (from the London Gazette, 1684).

The first appearances we’ve found of the modern spelling “bomb,” without the “e” on the end, are from a 1680 edition of The Turkish History, by Richard Knolles. The word “bomb” appears more than a dozen times, as both noun and verb.

Here’s a noun example: “twenty of them were killed that day by one Bomb.” And here’s one with the verb: “the Captain General form’d all the Trenches and Traverses for an Attack, and Bomb’d the Town with twenty Mortar-pieces.”

By the mid-1690s the “bomb” spelling had become established enough to appear in an English-to-French dictionary, Abel Boyer’s A Complete French Mastery for Ladies and Gentlemen (1694): “a bomb, une bombe.” That final silent “b” remained in the word, probably for etymological reasons, forever after.

The pronunciation of “bomb” has varied over the centuries, and it still does. Today three pronunciations are considered standard, according to the OED.

The dictionary, using the International Phonetic Alphabet, gives them as /bɒm/, /bʌm/, and /bɑm/, which we might transcribe as BOM, BUM, and BAHM (the first two are British, the third American).

The three vowels sound, respectively, like the “o” in “lot,” the “u” in “cup,” and the “a” in “father.” Furthermore, the British pronunciations are short and clipped in comparison with the American, which is more open and drawn out.

The second British pronunciation, BUM, was “formerly usual” in the British Army, Oxford says. And it apparently was widespread in the 18th century, since it’s the only pronunciation given in several dictionaries of the time, including the most popular one, John Walker’s A Critical Pronouncing Dictionary (1791).

As for the BOOM pronunciation, “bomb” was sometimes spelled “boom” or “boomb,” suggesting that it was pronounced that way too. The OED cites both spellings in an anonymous 1692 diary of the siege and surrender of Limerick: “600 Booms” … “800 Carts of Ball and Boombs.”

And the dictionary points readers to rhymes in poetry, where “bomb” is sometimes rhymed with “tomb” and “womb,” which were pronounced TOOM and WOOM at the time.

Here’s an Oxford citation from “The British Sailor’s Exultation,” a poem Edward Young wrote sometime before his death in 1765: “A thousand deaths the bursting bomb / Hurls from her disembowel’d womb.”

We’ve found a couple of additional examples in poetry of the 1690s.

In a 1692 poem written in rhyming couplets and based on Virgil’s Dido and Aeneas, John Crown rhymes “bomb’d” with “entomb’d.” Here are the lines: “The wealthy Cities insolently bomb’d, / The Towns in their own ashes deep entomb’d.”

And Benjamin Hawkshaw’s poem “The Incurable,” written in rhyming triplets, rhymes “womb,” “tomb,” and “bomb.” These are the lines: “It works like lingring Poyson in the Womb, / And each Day brings me nearer to my Tomb, / My Magazin’s consum’d by this unlucky Bomb.” (From Poems Upon Several Occasions, 1693.)

What’s more, the word “boom” (for a loud hollow noise) was sometimes spelled “bomb” or “bombe,” which suggests that the pronunciations occasionally coincided.

This example, cited in the OED, is from Francis Bacon’s Sylva Sylvarum, a natural history, or study of the natural world, published in 1627, a year after his death:

“I remember in Trinity Colledge in Cambridge, there was an Vpper Chamber, which being thought weake in the Roofe of it, was supported by a Pillar of Iron … Which if you had strucke, it would make a little flat Noise in the Roome where it was strucke; But it would make a great Bombe in the Chamber beneath.” (We’ve expanded the citation to give more context.)

And we found this example in a work that discusses sound production, Walter Charleton’s A Fabrick of Science Natural (1654): “As in all Arches, and Concamerated or vaulted rooms: in which for the most part, the sound or voyce loseth its Distinctness, and degenerates into a kind of long confused Bombe.”

In short, it’s safe to say that that “bomb” was probably pronounced BOOM by some educated speakers in the 17th century.

As we’ve noted, the word didn’t appear until 1588, during the modern English period. As far as we know, the final “b” was never pronounced. But the other words you mention, “womb” and “tomb,” are much older, and the “b” in their spellings was originally pronounced.

In the case of “womb,” a Germanic word that dates back to early Old English, it originally had a different vowel sound, too. But beginning in the Middle English period (roughly 1150 to 1500), the “oo” vowel sound developed and the “b” became silent.

As for “tomb,” a Latin-derived word that English borrowed from the French toumbe around 1300, it came with the “oo” vowel sound, and the “b” became silent in later Middle English. The “b” remained in the spelling, though in the 16th and 17th centuries the word occasionally appeared as “toom” or “toome,” according to OED citations.

Several other words ending in “b” (“lamb,” “dumb,” “comb,” “climb,” “plumb”) originally had an audible “b,” but it became silent during the Middle English period. Linguists refer to this shift in pronunciation from “mb” to “m” as an example of “consonant cluster reduction.”

We wrote a post in 2009 about other kinds of spelling puzzles—why “laughter” and “daughter” don’t rhyme, and why silent letters appear in words like “sword” and “knife.” And in 2017 we discussed “-ough” spellings (“enough,” “ought,” “though,” “through,” etc.), which are pronounced in many different ways.

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