Master
Head Of Household, Leader
noun
This has a similar meaning to 主人 (head of household). You can remember it also as the meaning you learned with the kanji 主, which is master.
The reading is of course different from what you learned with the kanji. Think of this:
The person who was your head of household was very strict. Anytime you did anything that was incorrect or bad, he/she would pull out the noose (ぬし), but would call it a "noosey" to be cute, since you were just a kid.
この家の主の名前は何ですか。
What is the name of the head of this household?
あの城の主にはあとつぎがいないらしい。
I heard that the master of that castle doesn't have any heirs.
この池には、古池の主と呼ばれる大きな殿様蛙がいると言われています。
It’s said that in this pond there is a huge leopard frog called the master of the old pond.