To keep something hidden inside oneself; to conceal feelings, thoughts, plans, or potential from others.
彼は大きな野心を秘めている。
He harbors great ambitions.
その歌手は胸に秘めた思いを歌にした。
That singer put feelings hidden in her heart into a song.
本当の意図を秘めたまま、彼は質問に答えた。
Keeping his true intentions concealed, he answered the question.