For words that have only 3 letters, there is not any 4th letter. Such as with the word “include”, there isn't any more letters Later on and therefore should be the word "add". The word “addict” is while in the BIP39 wordlist however you might have made use of “addi” https://dmozbookmark.com/story18854179/little-known-facts-about-bip39-seed-phrase-list