For words that only have three letters, there isn't any 4th letter. One example is with the word “increase”, there aren't any much more letters afterwards and therefore has to be the word "incorporate". The word “addict” is in the BIP39 wordlist however , you might have applied “addi” for https://bookmarklayer.com/story18851811/the-ultimate-guide-to-bip39-seed-phrase-mnemonics-generator