Young
Youthful
い adjective
This is a single kanji with an い on the end, meaning you know it's probably an adjective. What's the adjective form of young? It's young.
The reading is the same as the one you learned with the kanji. Oh how nice it is to be young and to be able to remember that.
ビエトは若い時、あるやみ取引でかなり利えきを上げました。
Viet made a considerable profit on a black market deal when he was young.
コウイチは若いころ、日本に留学していたことがあります。
Koichi studied in Japan when he was young.
あの若い女性は、あなたには到底手の届かない高嶺の花だってことに気づいてるわよね。
You do realize that young woman is way out of your league, right?