For words that only have 3 letters, there is no 4th letter. For instance with the word “incorporate”, there isn't any a lot more letters afterwards and therefore has to be the word "incorporate". The word “addict” is within the BIP39 wordlist but you would've utilised “addi” for “addict”. When https://bookmarkfox.com/story4499531/new-step-by-step-map-for-ledger-seed-phrase-bip39