The same word for "pray" (halah) is used in all three verses (Zechariah 7:2; 8:21-22). In this case, it means "to correct," "to stroke one's face," "to strive to please verbally." It could even mean "to please by appearance" because it is occassionally translated "supplicate," which generally implies "to bend low."
The attitude here is entirely different from that in Psalm 55:17-21. In this case, the people are trying to ingratiate themselves, to change the mind of one that they love back toward them. That is why people are coming to Jerusalem: The One that they love is being appealed to. So it will be translated from time to time "supplicate," "beseech," "entreat," or "make suit to."
This word is used in a wide variety of contexts. In one case, the same word will be translated "infirmity" or "sick," when a person is in a state of physical weakness. In another example, it is a weakness of spirit. A person feels he is on the outs with God, and he begs for forgiveness and appeals to Him for mercy.
John W. Ritenbaugh
What Is Prayer?