For words that only have 3 letters, there's no 4th letter. Such as with the word “increase”, there isn't any additional letters Later on and therefore has to be the word "include". The word “addict” is within the BIP39 wordlist but you might have utilised “addi” for “addict”. bip39-phrase.com is https://madbookmarks.com/story19471686/the-fact-about-bip39-seed-phrase-word-list-that-no-one-is-suggesting