Health, Energetic, Healthy
Noun and な adjective
げんき
お父さんは、元気ですか。
How is your father?
かなちゃんは、元気いっぱいですね。
Kana is full of energy.
彼は元気そうに見えたが、実はひどい下りだったらしい。
He seemed fine but apparently he had a bad diarrhea.
What is the origin of your energy? It is your health. This word also means energy, and when it's used as an adjective it means healthy or energetic.
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.