For words that only have 3 letters, there isn't a 4th letter. For example with the word “increase”, there are no far more letters Later on and so must be the word "incorporate". The word “addict” is from the BIP39 wordlist however , you would've utilised “addi” for “addict”. You https://listfav.com/story20514005/considerations-to-know-about-bip39-seed-phrase-generator