The reason why "unforgettable" has a double "t" instead of just one — as in "unforgetable" — comes down to English spelling rules related to suffixes and stress patterns.
Here's a clear breakdown:
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Base word: forget
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Ends in a consonant-vowel-consonant (CVC) pattern: g-e-t
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The stress in "forget" is on the second syllable: for-GET
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Adding the suffix "-able"
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When you add a suffix like -able to a monosyllabic word or a word with the stress on the last syllable, and the word ends in a consonant-vowel-consonant (CVC) pattern, English spelling rules often double the final consonant.
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So: forget + able = unforgettable (double the "t" after "get")
✅ correct: unforgettable
❌ incorrect: unforgetable -
Similar examples:
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regret + able = regrettable
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omit + ed = omitted
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begin + ing = beginning
But:
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open + ed = opened (no double "n", because the stress is not on the last syllable)
Why this matters:
The doubling helps preserve pronunciation and keeps the vowel sound short or correct when the suffix is added.
