From BiblePortal Wikipedia

Morrish Bible Dictionary [1]

One of the messengers sent to the house of God in the fourth year of king Darius, to pray and to enquire concerning the continuation of fasting in the fifth month (probably in commemoration of the destruction of the temple, etc.,  2 Kings 25:8-10 ). God's answer was that they had not fasted to Him.  Zechariah 7:2-5 . The name is really Persian and is identical with that of Sharezer, son of Sennacherib in  2 Kings 19:37;  Isaiah 37:38 .

Fausset's Bible Dictionary [2]

Sent with Regem Melech by the Jews of the country to "the house of God," i.e. the congregation of priests at Jerusalem ministering at the altar, (The Temple Was Not Yet Completed) , to ask whether they should still observe the fast on the tenth day of the fifth month, the anniversary of the burning of the temple. Their fast had been a mere act of self imposed and hypocritical will worship, to please themselves, not the Lord ( Zechariah 7:2).

Smith's Bible Dictionary [3]

Shere'zer. (Prince Of Fire). One of the people's messengers, mentioned in  Zechariah 7:2.

Holman Bible Dictionary [4]

 Zechariah 7:2

Easton's Bible Dictionary [5]

 Zechariah 7:2

International Standard Bible Encyclopedia [6]

she - rē´zẽr (  Zechariah 7:2 the King James Version). See Sharezer .