For words that only have 3 letters, there is absolutely no 4th letter. For instance with the word “incorporate”, there won't be any much more letters Later on and thus should be the word "increase". The word “addict” is while in the BIP39 wordlist however you might have employed “addi” https://bookmarkforest.com/story19538256/new-step-by-step-map-for-ledger-seed-phrase-bip39