Monarchy
noun
One ruler is the master of this entire country. Why, this sounds quite like a monarchy to me.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
ハプスブルク君主国
Hapsburg Monarchy
この町はかつて君主国だったそうです。
This town was once a monarchy.
君主国は王や女王がリーダーの国のことです。
A monarchy is a country where the leader is a king or queen.
デンマークは君主国です。
Denmark is a monarchy.