For words that only have 3 letters, there's no 4th letter. One example is with the word “incorporate”, there won't be any a lot more letters afterwards and therefore need to be the word "increase". The word “addict” is while in the BIP39 wordlist however, you would have utilized “addi” https://wisesocialsmedia.com/story4365547/little-known-facts-about-bip39-seed-phrase-list