For words that have only three letters, there is no 4th letter. For example with the word “incorporate”, there aren't any additional letters Later on and thus should be the word "incorporate". The word “addict” is from the BIP39 wordlist but you would have applied “addi” for “addict”. You may https://socialwoot.com/story20461279/bip39-phrase-generator-can-be-fun-for-anyone