For words that only have 3 letters, there is no 4th letter. For instance with the word “include”, there are no a lot more letters afterwards and so must be the word "add". The word “addict” is within the BIP39 wordlist however , you might have made use of “addi” https://webcastlist.com/story20034703/ledger-seed-phrase-bip39-no-further-a-mystery