For words that have only 3 letters, there isn't a 4th letter. By way of example with the word “increase”, there are no far more letters Later on and thus needs to be the word "incorporate". The word “addict” is within the BIP39 wordlist but you might have utilized “addi” https://e-bookmarks.com/story4426252/the-ultimate-guide-to-bip39-seed-phrase-mnemonics-generator