For words that have only three letters, there isn't any 4th letter. By way of example with the word “incorporate”, there aren't any much more letters afterwards and therefore should be the word "incorporate". The word “addict” is within the BIP39 wordlist but you might have utilized “addi” for “addict”. https://socialclubfm.com/story9532562/ledger-seed-phrase-bip39-no-further-a-mystery