Mystery Solved! Case Closed!
I love a good mystery. Not the Agatha Christie, whodunnit kind, but life mysteries. Is there life after death? Should I have pushed my kids more when they were younger? Why is my cat so fat? Why is there a silent <b> in aplomb? I may never know the answers to the first three, but I’m pretty sure I can figure out the answer to the last one. Allow me to build my case.
Silent letters are the curse of any English speaking nation. It’s not so much the speaking that’s the problem because, hello, the letters are silent. It’s having to write the damn things! What in damnation are they doing there? Despite what many a challenged speller might think, they are not there to make your existence miserable. One reason they are there is because they hold a place in the base element of a word for when they are needed in a related word. It’s called a morphological marker. I like to think of these markers not so much as “silent” as “unpronounced.” Silence seems so definitive and damning. “Unpronounced” gives them a little more potential to speak up in the right lexical environment. Consider these word pairs from select word families: sign~signal, soften~softer, crumb~crumble, muscle~muscular, and my favorite pterodactyl~helicopter (helic + o + pter). But what’s happening in <aplomb>?
My first stop in solving this word mystery was at the brilliant word detective agency of Merriam and Webster. Their entry for <aplomb> has a “Did You Know” section. I LOVE THE “Did You Know?” SECTION! When I come across one of these delicious morsels it’s like hitting the jackpot. I feel giddy and I mentally snuggle into a bed full of blankets and stuffed animals like a kid waiting for their bedtime story. Once upon a time in 1818 we adopted <aplomb>, meaning “composure,” from the French. It came from the Middle French phrase a plomb meaning “vertically”. But this word has not changed since we adopted it. When we adopt a word into our language and we don’t anglicize it (put our English spin on it), it’s called a loan word. <aplomb> has no other immediate family member in our language. None. So it can’t have any related words in which the <b> says “buh”. Thus, the <b> cannot be a morphological marker like in the previously stated word pairs. Hmmmmm. Still a mystery as to what it’s doing there.
Reading further into this word’s lineage, M-W tells me it descended from Latin plumbum. Go ahead and laugh at that one. Plumbum means “lead,” as in the metal, and not the particular shape of a particular anatomy. From this word we also get <plumb> “a lead weight attached to a line used to get a vertical direction,” which is used in general construction terminology. In more specific construction terminology, we have plumbers who do plumbing and plumb things. According to Wikipedia, plumbers during the time of the Roman Empire were named so because the original pipes in Rome were made of lead. A plumber back then was called a plumbarius which was at some point in time shortened to <plumber>. Other words in the <plumb> family are <plumbic>, <plumbous>, <plumbate>, and <plumbaginous>. Wait . . . did you hear that? Was that a “buh” sound in those words? All having to do with lead, and all words in which the once silenced <b> has its say. On this side of the family tree, the <b> is working as a morphological marker. But still, what about the /b/ in <aplomb>
Every letter has a reason for being in a word. If a letter is unpronounced and it’s not influencing the sound of another letter (phonological marker) or holding a place in a morpheme (morphological marker), then it could very well be an etymological marker. An etymological marker is a letter that links a word to its historical relatives. Some letters got there because Scribes way back when began reinserting letters from Latin root words back into English words to mark a meaningful connection. This is the case with plumb as reported by M-W. Scribes were not the only ones finding the <b> important enough to keep around. Scientists threw their weight behind it by giving lead the chemical symbol Pb.
So while <plumb> and <aplomb> don’t share the same modern day structure, they do share a Latin root and a figurative meaning. Words with a <plumb> base pertain to lead or literally to verticalness as tested by dropping a lead weight. <aplomb> shares the figurative meaning of verticalness by referring to someone who holds themselves upright with easy confidence. Because <plum> and <aplomb> share a meaning, a Latin root, but not structure (there’s that o/u switcharoo going on), I would say they are cousins. So why is there a silent <b> in aplomb?
Allow me to summarize the facts before presenting my conclusion.
<aplomb> is a French loan word
<aplomb> has no immediate family in English
because of this, the <b> cannot be a morphological marker because there are no immediate relatives in which <b> makes a sound
<aplomb> is a cousin to the <plumb> family sharing meaning and the Latin root plumbum, but not structure due to the <o> and <u> difference
the <b> in the <plumb> family IS a morphological marker
Thus, we can conclude that the unpronounced <b> is there to act as an etymological marker marking a connection to the <plumb> family and the Latin root plumbum. So there you have it. Your honor, I rest my case.