The reason why "unforgettable" has a double "t"

 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:

1. Base word: forget

   • Ends in a consonant-vowel-consonant (CVC) pattern: g-e-t

   • The stress in "forget" is on the second syllable: for-GET

2. Adding the suffix "-able"

   • 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.

   • So: forget + able = unforgettable (double the "t" after "get")

   ✅ correct: unforgettable
   ❌ incorrect: unforgetable

Similar examples:

• regret + able = regrettable

• omit + ed = omitted

• begin + ing = beginning

But:

• 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.