You will keep in perfect peace those whose minds are steadfast, because they trust in you. (Isaiah 26:3 NIV)
According to the article in Our Daily Bread, the Hebrew word translated as steadfast here means "to lean upon." So I had a look at the original verse:
The word corresponding with steadfast is the second one from the right. In KJV, it is translated as "stayed (on thee)".
Thou wilt keep [him] in perfect peace, [whose] mind [is] stayed [on thee]: because he trusteth in thee. [Isaiah 26:3 KJV]
- The first and third words have the same consonants.
- The fourth and fifth words are exactly the same: shalom shalom (perfect peace).
This video says that shalom basically means "complete" and "whole".
Indeed we are broken people living in a broken world, and we long for shalom for all of us.