For words that only have 3 letters, there isn't any 4th letter. For example with the word “increase”, there isn't any far more letters Later on and therefore should be the word "increase". The word “addict” is inside the BIP39 wordlist however , you might have utilized “addi” for “addict”. https://getsocialpr.com/story20022223/invalid-bip39-phrase-things-to-know-before-you-buy