For words that have only 3 letters, there is not any 4th letter. One example is with the word “incorporate”, there are no much more letters Later on and therefore should be the word "increase". The word “addict” is inside the BIP39 wordlist but you would've utilized “addi” for “addict”. https://infopagex.com/story4141078/the-5-second-trick-for-ledger-seed-phrase-bip39