Dual
Noun and の adjective
にじゅう
分からないかん字の下に、二重せんを引いてください。
Please draw double lines under kanji you don’t know.
日本は二重国せきをみとめていません。
Japan doesn't allow dual citizenship.
「それでは、世間話はそれぐらいにして、本題に入ろう。今日の議題は何だったかな？」「今日はあなたの二重あごについて話しをすることになっています。」「そうだったな。それでは始めようか。」
"Well, let’s stop the small talk and cut to the chase. What was the topic of today’s meeting?" "We were going to talk about your double chin, sir." "Right, right. Let’s get started."
When you have two heavy things, you have double and dual the heavy (compared to one, at least).
This word is a prefix attached to other words to show that it is "double." 二重 kanji time!
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.