For words that have only 3 letters, there is not any 4th letter. For example with the word “include”, there won't be any a lot more letters afterwards and thus have to be the word "add". The word “addict” is while in the BIP39 wordlist however, you would have applied https://bookmarkassist.com/story19509644/new-step-by-step-map-for-ledger-seed-phrase-bip39