Correct spelling, explanation: the word eighteen is a compound of the word eight and teen, so it’s created the same as other words with teen. You may have noticed that despite one word ending in t, and the other beginning with t, eighteen only has one t in the middle. This is because even if we spelled out both letters, it would be very impractical as we don’t double this sound when we say eighteen out loud. And if we only read one t, without an accent or any other significant difference, there is no need to include both letters.

Definition of eighteen:
noun
1. number 18
We did not have many guests, there may have been around eighteen, maybe twenty guests.
When I was eighteen I moved out from my parent’s place, but my daughter is twenty and still lives with me.

Incorrect spelling, explanation: the word eighteen is made up of the words eight and teen. It seems obvious that putting them together should make it eightteen, but it’s actually incorrect. This is because in the pronunciation of eighteen we do not in any way accentuate the double t, as it would be very uncomfortable to say. And in general, people try to simplify the language so it’s intuitive and comfortable for the speaker, hence we dropped one t.

Incorrect spelling

Incorrect spelling

Incorrect spelling

Incorrect spelling