What does "deceitful" mean in Jeremiah 17:9, and in Jer. 17:10 what do "heart" and "reins" mean?

What does "deceitful" mean in Jeremiah 17:9, and in Jer. 7:10 what do "heart" and "reins" mean?  

Jeremiah Chapter 17

9 The heart [is] deceitful above all [things], and desperately wicked: who can know it?

10 I the LORD search the heart, [I] try the reins, even to give every man according to his ways, [and] according to the fruit of his doings.

Jeremiah 17:9 - 10

ESV - ⁹ The heart is deceitful above all things, and desperately sick; who can understand it? ¹⁰ "I the Lord search the heart and test the mind, to give every man according to his ways, according to the fruit of his deeds."

Clarify • Share • Report • Asked January 07 2021 • Jack Gutknecht