o is an address particle used before a person or group, and it can also introduce an exclamation.

Across the supplied verses, this particle introduces direct address to a person or group, whether in instruction, rebuke, praise, or argument; it also introduces the exclamation over God's riches, wisdom, and knowledge in Romans 11:33.

1. Particle introducing address or exclamation · dominant

   The supplied morphology identifies both forms as Interjection or Particle. In 1 Timothy 6:20 the APB renders direct address to Timothy, in Galatians 3:1 it addresses the Galatians before a rebuke, and in Matthew 15:28 it addresses a woman before affirming her faith; in Romans 11:33 the APB renders an exclamation over God's riches, wisdom, and knowledge.

   1 Timothy 6:20Galatians 3:1Matthew 15:28Romans 11:33Romans 2:1Luke 9:41

In the Anselm Project Bible: The APB commonly marks the particle with “O” before an addressed person or group, as in 1 Timothy 6:20 and Romans 2:1, and with “Oh” in Romans 11:33. These renderings only indicate how the clauses are presented.