For words that only have 3 letters, there is no 4th letter. Such as with the word “increase”, there aren't any more letters afterwards and so has to be the word "include". The word “addict” is from the BIP39 wordlist however you would've applied “addi” for “addict”. Standard recovery phrases https://bookmarklinx.com/story19231304/the-fact-about-bip39-seed-phrase-word-list-that-no-one-is-suggesting