For words that only have three letters, there is absolutely no 4th letter. For instance with the word “incorporate”, there are no additional letters afterwards and therefore should be the word "increase". The word “addict” is while in the BIP39 wordlist but you might have made use of “addi” for https://sociallweb.com/story4292577/helping-the-others-realize-the-advantages-of-bip39-mnemonic-phrase-tool