on high, in the highest

Definition

The terms "on high" and "in the highest" are idioms that mean, "in heaven."

Another meaning for the idiom "in the highest" could be, "the most honored."
The phrase, "on high" can also refer to being high in the sky, such as a bird's nest that is on high. In that context it could be translated as, "high in the sky" or "at the top of a tall tree."
The word "high" also indicates the elevated location or importance of a person or thing.
The phrase "from on high" could be translated as "from heaven."