Not many letters get to be words.
I can only think of three: A, I, and O.
As in, “O Lord, I have a problem.”

O!

We usually write this word with an “h” (oh!) but it means the same thing with or without the “h”. The original biblical languages of Hebrew and Greek don’t include the word “O”, but there are markings in the text that indicate intense emotion, which translators express as “O”.

Every time you come across an “O” in your Bible reading, give your voice a little oomph, a small burst of energy, a bit of zing. The Holy scriptures are not monotone. They are full of power and life, so read them with zest and zeal. Especially the “O”s.

It can mean awestruck wonder.
“O Lord, how majestic is your name in all the earth.” Ps. 8:1

It can mean spirited approval.
“O Lord my God, you are very great.” Ps. 104:1

It can mean desperation.
“How long, O Lord? Will you forget me forever?” Ps. 13:1

It can mean urgency.
“Arise, O Lord, in your anger.” Ps. 7:6

It can mean exasperation.
“Answer me when I call to you, O God.” Ps. 4:1

It can mean joy.
“Praise the Lord, O my soul.” Ps. 146:1

Jesus said it.
“Why are you afraid, O you of little faith?” Matt. 8:26

Paul said it.
“O death, where is your victory? O death, where is your sting?” 1 Cor. 15:55

The angels in heaven say it.
“Just are you, O Holy One, who is and who was.” Rev. 16:5

Oh, such a versatile little word that packs a punch with just a breath!
My favorite word in the Bible that starts with “O” is “O”.