The first use of the verb “k.p.r” is in the story of Noah, when God instructs Noah
עֲשֵׂה לְךָ תֵּבַת עֲצֵי־גֹפֶר קִנִּים תַּעֲשֶׂה אֶת־הַתֵּבָה וְכָפַרְתָּ אֹתָהּ מִבַּיִת וּמִחוּץ בַּכֹּפֶר׃
“Make yourself an ark of gopher wood; make it an ark with compartments, and cover it inside and out with pitch.” (Genesis 6:14)
Here the root of the word appears to mean both“ to cover”, and, since the word for pitch uses the same root – “pitch – some kind of waterproof and protective covering- so we can extend this meaning to “to protect”
We find an echo of Noah’s “ark” in the ark made for the tent of meeting, the place where the presence of God will hover: For this “aron” too is to have a protective covering – the kapporet (exodus 25:17-21) – the mercy seat that covers and protects the ark and the stones within it, decorated with cherubim to the sacrifices of atonement to be made by the high priest.
When we come to the more usual formations of the verbal root, it is generally found in Temple artefacts and ritual – almost always in the plural and in the piel or hitpael binyan , and almost always to do with the sacrifices to be made there to atone for the sins of the people, either as individuals or as a collective.
Altogether the root appears over a hundred times in Tanakh, and from its earliest and most “material” form in the “kal” binyan that we find in Noah, it grows to have meanings or undertones of “covering” or “protecting”, “appeasing”, “ransoming”, or a “reconciliation”.
What does it mean for us today, that we name our holiest day of the year after this verbal root with meanings of to cover over and protect, to appease and to ransom, to reconcile?
I think it means that we recognise that we cannot undo the past – but we can come to terms with it, and we refuse to allow it to define us and our future. We can create a kapporet – a protective “lid” or closure between us and what has happened– to enable us to let go of the damage or pain we have been carrying, and to accommodate out reality as we move into the future.