government by the worst persons; a form of government in which the worst persons are in power.
I'll bet nobody expected Britain to become one of these when the word was first coined:
1829, "government by the worst element of a society," coined on analogy of aristocracy from Gk. kakistos "worst," superl. of kakos "bad" (which is perhaps related to the general IE word for "defecate") + -kratia "rule of," from kratos "strength, power, rule" (see -cracy).