Atonement as covering?

The Ark of God Carried into the Temple

Les Très Riches Heures du duc de Berry, Folio 29r

Musée Condé, Chantilly

Place of the Kaporet

(Image from Wikipedia)

Last Sunday during Bible study, the topic of "atonement" came up in discussion, and one of the participants noted that the word literally means "at onement" and that the word "atone" is a back formation from the word "atonement."

I was skeptical and wondered if this were a folk etymology, but I'll be damned if it isn't right!

Or at least partly right. The Online Etymological Dictionary says this about "atone":

1555, from adv. phrase atonen (c.1300) "in accord," lit. "at one," a contraction of at and one. It retains the older pronunciation of one. The phrase perhaps is modeled on L. adunare "unite," from ad- "to, at" + unum "one." Atonement is 1513; theological sense dates from 1526.

This implies that the verb "atone" is no back formation from the noun "atonement" but has its origin in the adverbial phrase "atonen" -- which, by the way, doesn't look like a phrase to me, but I suppose that the lexicographers meant that "atonen" is an adverb formed from the prepositional phrase "at one."

As for the word "atonement," it seems to have been coined by William Tyndale (c. 1494-1536) for his 1526 English Bible to translate the meaning inhering in the Hebrew word "kaphar."

According to the online Blue Letter Bible, "kaphar" has the following meanings:

כפר kaphar

1) to cover, purge, make an atonement, make reconciliation, cover over with pitch
a) (Qal) to coat or cover with pitch
b) (Piel)
1) to cover over, pacify, propitiate
2) to cover over, atone for sin, make atonement for
3) to cover over, atone for sin and persons by legal rites
c) (Pual)
1) to be covered over
2) to make atonement for
d) (Hithpael) to be covered

Also at the Blue Letter Bible site is the Gesenius Hebrew and English Lexicon, which gives the basic meaning of "kaphar" as "to cover, to cover over."

According to Wikipedia's entry on "atonement" (as of November 30, 2008), "Tyndale thought that if [the meaning behind "kaphar" were] translated as "reconciliation," there would be a pervasive misunderstanding of the word's deeper significance to not just reconcile, but "to cover," so the word ["atonement"] was invented."

I confess that I do not understand this. The word "atonement" does not convey any sense of "covering" -- not so far as I can see. Either Wikipedia is wrong (which is definitely possible), or I am wrong (also possible, for I was wrong about the etymology of "atonement").

Perhaps some of the Bible experts who occasionally visit this blog can help me out on this rather puzzling choice of "atonement" to capture the sense of "covering" inherent in the Hebrew term.