For words that have only 3 letters, there's no 4th letter. Such as with the word “incorporate”, there are no far more letters afterwards and therefore must be the word "include". The word “addict” is during the BIP39 wordlist however you would have used “addi” for “addict”. This short article https://bookmarkvids.com/story20459842/invalid-bip39-phrase-things-to-know-before-you-buy