Central America has its cartels, Italy its mafias, and Japan its yakuza. But where does the word yakuza come from? Obviously Japanese, but to go further one must know the card game Oicho-Kabu. It's very traditional, played with a set of kabufunda cards. The worst possible card combination you can have in the game is an eight, nine, and three, or in Japanese, ya, ku, and za (pronunciations of numbers vary in Japan; these are the forms used here). Therefore, yakuza is something extremely "unlucky", very much like crossing the yakuza. As separate components, ya, ku, and za don't go very far etymologically (being so simple); they simply trace back into Japanese, or Chinese, or Korean, or a mixture of all three, retaining their definitions as they do so. Side note: the yakuza are also called gokudo, but they call themselves ninkyo dantai and the police call them boryokudan.
Adam Aleksic, a freshman studying linguistics at Harvard University, has been described as the internet's sixth most famous etymologist. He has disturbing interests in words, vexillology, geography, board games, limericks, and law, and he loves writing about himself in the third person.
The Etymology Nerd