For words that only have 3 letters, there is not any 4th letter. For example with the word “insert”, there isn't any a lot more letters afterwards and thus need to be the word "increase". The word “addict” is inside the BIP39 wordlist however , you would've applied “addi” for https://one-bookmark.com/story18892211/examine-this-report-on-bip39-mnemonic-phrase-tool