pronunciation - Why is "cupboard" pronounced with a silent "p"?

According to Google at least, the word "cupboard" originated in late Middle English as denoting a board that held cups. Since then, the word has evolved to mean a kind of cabinet.

My question is, given its origin and spelling, why do we pronounce "cupboard" with a silent "p"? Has the pronunciation simply evolved because "cup-board" is too awkward to say, or is there a deeper pronunciation rule that I'm not aware of?

Answer

There are sev­er­al fac­tors in play here.

Dif­fi­cult con­so­nant clus­ters are of­ten re­duced in rapid speech or over time; think of friend­ship, spend­thrift, twelfth, months.

Much of the dif­fer­ence be­tween an un­voiced and a voiced stop in English is ac­tu­al­ly not its voic­ing but its as­pi­ra­tion, and be­cause one nor­mal­ly on­ly as­pi­rates stops that are both un­voiced and which be­gin a stressed syl­la­ble, you have just lost the prin­ci­pal dis­tin­guish­ing fea­ture.

When you have two con­sec­u­tive stops that dif­fer on­ly in voic­ing, these are es­pe­cial­ly like­ly to fuse, with the first of the pair dropped. Without an au­di­ble re­lease, there is noth­ing to mark the end of one and the be­gin­ning of the next.

Here is a set of words or phras­es where you nor­mal­ly sup­press one of the two ad­ja­cent stops that dif­fer on­ly in voic­ing:

• cup­board


• rasp­ber­ry


• black­guard


• back­ground


• post­doc


• post­dat­ed check


• sub­poe­na


• next-door neigh­bor


• last-ditch ef­fort


• best dog­sit­ter

It is not al­ways the first of the two that is sup­pressed. For ex­am­ple, no­tice how in back­ground noise, it is the g that ap­pears to get lost: it sounds more like back round.

In con­trast, in black­guard (when pro­nounced as though it were spelled blag­gerd) it is the first of the two ad­ja­cent stops that seems to go away, mak­ing it work like cup­board and rasp­ber­ry with their lost p.

A lost dog may well come out sound­ing like a loss dog in rapid speech, and a black glass like a black lass.

This is not com­plete­ly guar­an­teed, es­pe­cial­ly in new com­pounds whose mor­phemic bound­aries are still clear. It is al­so more apt to hap­pen when the stress is on the first syl­la­ble than when it’s on the sec­ond. But on­ly very care­ful speak­ers will gem­i­nate stops when go­ing out­doors: the t be­comes at most a glot­tal stop — if that. So an out­door the­ater might be said [ˌäʊ̯ʔ.doɻʷ ˈθiː.əɾɚ].

But even a big kite, a bad turn, or a job posting is li­able to lose the first of the paired stops in con­nect­ed speech, since the sec­ond stop is as­pi­rat­ed and the first gets no au­di­ble re­lease.