For words that have only 3 letters, there's no 4th letter. For instance with the word “increase”, there won't be any much more letters Later on and so have to be the word "add". The word “addict” is during the BIP39 wordlist however you would've used “addi” for “addict”. Meticulously https://bookmarkeasier.com/story18662000/examine-this-report-on-bip39-mnemonic-phrase-tool