Incorrect spelling, explanation: intrested may go along with pronunciation, but is an incorrect form. This is because the word interest originates in Latin interesse which is a merge of two words (inter + esse; literally in between), meaning to concern. Therefore the correct spelling is interested because e is present in the original spelling.

Correct spelling, explanation: this spelling may be confusing due to pronunciation, and we need to go deeper back to medieval Latin to understand the spelling. The core word for interested is interest, which originates interesse, literally in between (inter + esse – to be), meaning to concern. Thus the spelling of interested comes from the word inter, where e must be placed due to pronunciation. This vowel remained despite the transformation of the word, so intrested is incorrect.

Definition of interested:
adjective, engaged in something; curious, involved; characterized by interest in something
Joe isn’t interested in partying. He’s an introvert and would rather stay home.
Interested parties, in this case, decided to end it amicably.

Incorrect spelling

Incorrect spelling

Incorrect spelling