English spelling can be maddening, and no example proves this better than the trio: comb, bomb, and tomb. All three end in -OMB. None of them rhyme with each other.
The Three Pronunciations
Let that sink in: comb = /koʊm/ (rhymes with "home"), bomb = /bɑːm/ (rhymes with "calm"), tomb = /tuːm/ (rhymes with "room"). Same ending, three different vowels, and the B is always silent.
The Silent B Rule
At least one thing is consistent: the B in -MB at the end of a word is always silent. This applies to: comb, bomb, tomb, climb, lamb, thumb, dumb, numb, plumb, womb, crumb, limb.
Why the Vowels Are Different
COMB group: /oʊ/ (long O)
This is an old English pattern where the vowel is a long O diphthong. The B was once pronounced (Old English "camb") but dropped while the long O was preserved.
Same pattern: only "comb" is common in this group.
BOMB group: /ɑː/ (short O / "ah")
"Bomb" comes from a different source (ultimately from Greek "bombos" for a booming sound). The O is the open /ɑː/ sound of American English.
Same pattern: bomb is the main example in this group.
TOMB group: /uː/ (long OO)
"Tomb" comes from French/Latin "tumba." The vowel shifted to /uː/ over centuries, matching the French pronunciation pattern.
Same pattern: womb /wuːm/ follows this pronunciation too.
The Complete -MB Silent B List
| Word | Pronunciation | Vowel Sound |
|---|---|---|
| comb | /koʊm/ | long O |
| bomb | /bɑːm/ | "ah" |
| tomb | /tuːm/ | long OO |
| womb | /wuːm/ | long OO |
| climb | /klaɪm/ | long I |
| lamb | /læm/ | short A |
| thumb | /θʌm/ | short U |
| dumb | /dʌm/ | short U |
| numb | /nʌm/ | short U |
| crumb | /krʌm/ | short U |
| limb | /lɪm/ | short I |
| plumb | /plʌm/ | short U |
How to Remember
Unfortunately, you must memorize each word individually. There is no reliable rule to predict the vowel in -OMB words. But here is a mnemonic: Comb your hair at Home, a Bomb goes "BAM!", and a Tomb is a Room for the dead.
Why This Matters for Learners
This example shows a fundamental truth about English: spelling often reflects history, not pronunciation. Words from different origins (Old English, French, Greek) kept their different vowel sounds even when they ended up looking similar on paper. Knowing this helps you accept that some words simply need to be memorized individually.
Practice Sentences
- She found a comb near the tomb.
- A bomb destroyed the wall near the tomb.
- Use a comb, not your thumb.