For words that have only three letters, there is not any 4th letter. Such as with the word “incorporate”, there are no more letters Later on and thus need to be the word "include". The word “addict” is inside the BIP39 wordlist but you would've utilized “addi” for “addict”. This https://bookmarkilo.com/story18679439/the-ultimate-guide-to-bip39-seed-phrase-github