What speakers mean by it
A tomb, in ordinary English, is a place built or set aside for the dead: a vault, a chamber, a small stone house in a churchyard or inside a church. Dictionaries still allow a looser sense, a pit or grave, and a literary one in which the tomb simply stands for death. A person who will not talk can still be called a tomb, though that idiom has thinned. None of that is the oldest picture the word carried. The origin of the word tomb is a French loan that arrived with a mound in its past, not a native English coinage.
Borrowed after the Conquest
English did not inherit this noun from Old English. It borrowed it in the early thirteenth century, when Middle English writers were taking in large numbers of Anglo-French words for buildings, law, and church life. Manuscripts show tombe, tumbe, toumbe and a scatter of other spellings. The immediate source is Anglo-French tumbe, matching twelfth-century Old French tombe, already used for a monument, a gravestone, and a burial place.
French had the word from Late Latin tumba, with a medieval spelling tomba. Latin had taken it from Ancient Greek túmbos, a funeral mound and, by extension, a grave. The same Late Latin form feeds Italian tomba and Spanish tumba. Modern French tombeau, now the usual word for a built sepulchre, comes from a Vulgar Latin diminutive that English never made its main form.
Dates for first English use sit in a narrow band. Some references put the earliest forms near 1200; one historical dictionary’s earliest citation is around 1300, in a life of Thomas Becket. Other desk dictionaries date the noun to the thirteenth or fourteenth century depending on sense. The disagreement is about a few decades, not about the period. This is a Middle English borrowing.
Old English already had words for graves and coffins, among them þrūh, a trough-like coffin. The French loan did not fill an empty slot so much as take over the high-register name for a marked burial place.
The mound and the argument behind it
In Greek the core image is earth heaped over the dead. That mound sense is the oldest meaning we can hold with confidence. What lies behind the Greek noun is disputed.
Many English dictionaries, following a reconstruction associated with Calvert Watkins, connect túmbos to a Proto-Indo-European root meaning to swell. Handbooks write that root as *teue-, *tewh₂-, or *teuə-. If the link is real, a burial mound is a swelling of the ground, and Latin tumēre, to be swollen, belongs in the same family, along with tumulus, an earth hill or barrow, and English tumor. Thumb is sometimes listed on the same swell-root, as a thick digit.
Robert Beekes argued instead that túmbos is Pre-Greek: a word from a Mediterranean language that Greek absorbed, not an Indo-European inheritance. He pointed to Latin tumulus, Armenian t'umb (an earthen wall or landfill), Middle Irish tomm (a small hill), and Middle Welsh tom (a mound, also dung) as possible holders of the same older item. On that view the resemblance to tumēre may be coincidence, contact, or a later blending, not proof of a shared ancestral verb.
The two stories cannot both be simply true. Standard dictionaries still print the swell etymology with a cautious perhaps. Specialists in Pre-Greek print a different caution. The chain from Greek through Latin and French into English is not in doubt. The step before Greek is.
English tomb has no prefix or suffix to unpack. It is a simplex loan. The fact that does need explaining is the last letter. The modern spelling never matched the spoken word exactly. The final b fell silent around the time the spelling settled, in the same group as lamb and dumb. Speakers say a long vowel plus m; the written b still points at Greek -mbos and Latin tumba.
A verb tomb, to bury, is already Middle English. Entomb has since done most of that work.
How the sense moved
Greek starts with a mound. Late Latin keeps a sepulchral mound. Old French already covers monument and tombstone as well as the grave.
Middle English used the loan for several things at once: a structure for a corpse, a grave or burial mound, a coffin or sarcophagus, and a memorial stone. That range is original to the English word, not a later poetic stretch. Over the centuries the built chamber — walls, a roof, sometimes a door for a family vault — became the central sense. Grave stayed as the looser use.
By the 1550s the noun could stand for death or the close of earthly life. In American slang from 1840, the Tombs was a New York City prison, a nickname that treats a jail as a place of living burial. Tombstone and entomb are English formations on the borrowed noun, not extra French imports.
Archaeology later added type-labels: passage tomb, chamber tomb, beehive tomb. Those are classifying compounds. They do not change the etymology; they show how useful a general word for a marked burial became once fieldworkers needed names for kinds of mound and chamber.
There was no sharp break in meaning, only a slide from heaped earth to built resting place, then a figurative reach toward silence and death.
The letter English no longer says
Keep the silent b. It is the one piece of the spelling that still records the mound. Tomb entered English as a thirteenth-century French word for a Greek burial heap, and the consonant we stopped pronouncing is the one that still points back along that path.