For words that only have 3 letters, there isn't any 4th letter. Such as with the word “increase”, there won't be any far more letters afterwards and thus should be the word "add". The word “addict” is in the BIP39 wordlist however you would have used “addi” for “addict”. You https://socialnetworkadsinfo.com/story20228471/little-known-facts-about-bip39-seed-phrase-list