For words that only have three letters, there isn't any 4th letter. For instance with the word “increase”, there won't be any much more letters afterwards and therefore should be the word "add". The word “addict” is from the BIP39 wordlist however, you would have applied “addi” for “addict”. Keep https://bookmarkalexa.com/story4478316/the-5-second-trick-for-ledger-seed-phrase-bip39