For words that only have 3 letters, there is absolutely no 4th letter. For instance with the word “increase”, there aren't any extra letters afterwards and thus need to be the word "include". The word “addict” is in the BIP39 wordlist however, you would have applied “addi” for “addict”. Numerous https://meshbookmarks.com/story18874800/top-latest-five-bip39-seed-phrase-mnemonics-generator-urban-news