Hallows, anyone?

I’m definitely on the outside looking in on this one, but inquiring minds want to know: What is (or are) “hallows.”

Never mind “Deathly Hallows.” (Shouldn’t it – they? – be “Deadly”?)

Obviously I ask because “hallows” is a word much in the minds of a few million readers of “Harry Potter and the Deathly Hallows.”

I’m not a reader of Harry largely because I’m a non-fiction, non-fantasy sort of guy. Moreover, I read slowly, have a lot to do and my demographic is all wrong.

Typewriters, jazz, Quakerism, farmers markets … and Hallows?

Not even close, especially since I can’t find a logical contextual meaning for the word.

In the dictionary what I get isn’t a noun, but a verb.

HALLOW

transitive verb — hal·lowed, hal·low·ing, hal·lows

1. To make or set apart as holy.
2. To respect or honor greatly; revere.

Now certainly one of Harry’s hordes, who by now have read the book, can explain what this is all about.