A liberatarian catch-all used to describe a limited, functional
government that ensures an ideal
free society. The synonymity with 'monarchy' is unintentional and an ironic symptom; the true roots of "minarchist" are "minimal" and "archist", the later being a Greek derivation of "ruler".
"
Anarchy would be a society with no
government at all, while minarchy would be a society with a very "minimal government." - As quoted from an amateur
Libertarian essay that you can google easily.