秘 (Kanji for secret)

Onyomi

HE surely keeps his wheat secret, as if it was important to anyone else!

( に　or を ) ひ＊める

to hide, or conceal information, to keep something to one's self.
★★☆☆☆

秘密(ひみつ)	a secret ★★★★★ 秘 (secret) + 密 (hard to see) = 秘密 (a secret)
便秘(べんぴ)	constipation ★☆☆☆☆ 便 (convenient　/ poop) + 秘 (secret) = 便秘 (constipation)