The idol - i. e. the Asherah (2 Kings 21:7 note), which receives here (and in Ezekiel 8:3, Ezekiel 8:5) the somewhat unusual name of semel, which some regard as a proper name, and compare with the Greek Σεμέλη Semelē.
Related Commentaries of 2 Chronicles 33:7
2 Chronicles 33:7
7 And he set a carved image, the idol which he had made, in the house of God, of which God had said to David and to Solomon his son, In this house, and in Jerusalem, which I have chosen before all the tribes of Israel, will I put my name for ever: