The root of shalom is shalem, which means complete, whole, or finished in the sense of something that lacks nothing. When the Hebrew Bible says a sacrifice was shalom, it meant there was no defect in it — nothing absent that should be present. When a builder said a wall was shalom, it meant there were no gaps. When the text describes a city at shalom, it means that city is functioning as a city is meant to function: commerce, family, worship, governance, all in right proportion to each other.
This is why shalom was used as a greeting and as a farewell. When people said shalom to each other, they were not saying "I hope there's no conflict in your day." They were saying something closer to "may you be whole — may your family be intact, your health complete, your relationships right, your spirit settled." The greeting was a blessing and a wish simultaneously, compressed into one word.
Isaiah 53:5 uses shalom in a way that would have been unmistakable to its first readers: "the chastisement of our peace was upon him." The word there is shalom. The punishment that purchased our wholeness — our completeness, our nothing-missing, nothing-broken state — fell on the servant. The entire scope of what was broken in human life is in view, not merely the end of hostilities. When Paul in Philippians 4:7 writes about "the peace of God, which passeth all understanding," the concept behind the Greek eirene is shalom — because Paul was working from the Hebrew scriptures and the concept doesn't shrink when it enters Greek.
Numbers 6:24–26, the Aaronic blessing, culminates in shalom: "The LORD lift up his countenance upon thee, and give thee peace." That final word is the crown of the blessing. The whole structure of the blessing — protection, grace, presence — is all building toward shalom. It was not an afterthought. It was the goal.
Commentary is from a charismatic Protestant perspective, drawing on KJV text and public-domain sources including Spurgeon, Andrew Murray, and Matthew Henry.