For words that only have 3 letters, there is no 4th letter. Such as with the word “increase”, there won't be any more letters Later on and so needs to be the word "insert". The word “addict” is while in the BIP39 wordlist however you would've applied “addi” for “addict”. https://getsocialsource.com/story4431231/top-latest-five-bip39-seed-phrase-mnemonics-generator-urban-news