For words that have only three letters, there isn't any 4th letter. One example is with the word “incorporate”, there aren't any additional letters Later on and thus must be the word "incorporate". The word “addict” is inside the BIP39 wordlist however, you would've utilised “addi” for “addict”. Several Wallets:Should https://hypebookmarking.com/story18734579/bip39-seed-phrase-mnemonics-generator-an-overview