The Amazing History of "Hallowed"
"Hallowed" is a great word that's actually REALLY OLD. And you are probably still using it in ways you don't even realize.
It's no coincidence that "Hallowed" and "Holy" mean the same thing. As you say the two words out loud you can hear "hal" the Hebrew same "root" in both. Spelled הֵל in Hebrew ("HL"), "Hal" is also at the root of the familiar Hebrew word "Hallelujah" which means "praise God," or literally "Hallel-Yahweh."
In Hebrew, the word "hila" or "hala" -- written as "HL" in Hebrew, is translated into English as "halo." In both languages it means "an emanation or circle of light" in the sense of it being God's light or a "crown" of light. Not coincidentally, Greek and Latin share the same word "halos" which means a disk of light such as a halo around the sun, but also in the spiritual sense of divine presence.
In fact, ancient Hebrew's "HL" pre-dates and is likely the SOURCE of the word "Halos," and "Halo" and "Holy." Hebrew was one of the early written languages and its alphabet became the basis for many other emerging written languages. Israel also sat at a geographical crossroads which allowed both its writings and people to spread. Greek, Arabic (Aramaic), and eventually Latin (Roman) were influenced. And when the Hebrew scriptures were translated into Greek and spread by the ancient Church and its liturgies, many old words and word roots influence the languages of Europe. For example, Old Germanic, Old English, and even Old Norse all adopted the root "Hal" coming up with the word "halig" (holy) and perhaps even "hallo" (heil, hale, hello) in the sense of "blessings to you" or "God's presence be with you!" These languages used a form of "halo" to describe the halo seen around the sun or moon and imagined around the divine.
The Hebrew "HL" or "hal" may also be at the root of other familiar English words, such as "healthy," and "whole." ("may" -- etymology is full of debates).
As a teacher, I find it interesting that all these words "aspirate" (breath out), such that I can help my students feel the exclamation of "awe" seeing a halo around the sun or sensing the presence of God. "Ho!" or perhaps "Whoa! God!" 
To "hallow" something is to make it special and holy, to shine light on it, or let its light shine and encircle or embrace you. But when we say it in prayer, and keeping in mind its origins describing "light" perhaps "Hallowed be thy name" is asking, "Make this moment holy. Shine the light of your presence on me. Surround me, O Lord."
Why do so many people say it, "Hallo-WED" in the Lord's Prayer?
Good question! Habit? Tradition? Poetic cadence? The word is pronounced "hallow'd" not "hallo-WED." You wouldn't say, "we stand on hallow-WED" ground. You'd be hard-pressed to find ANY other time people say hallow-WED, other than the Lord's Prayer. But this isn't the first or last time religious people have inflected words to sound more "holy." Take for example, the preacher who says "Juh-EE-zus" instead of "Jesus," or "Guh-aw-duh" instead of simply, "God," or people who insist on praying words that nobody uses anymore, like "trespasses" and "thy."
So is it "Ay-men" or "Ah-men" ??? 
For more information:
See Oxford's etymology of "halo" at https://www.lexico.com/en/definition/halo
See https://en.wikipedia.org/wiki/...ligious_iconography) for a quick read about the use of "halo" in art and the history of light around the head in many other religions.
See a rabbi's discussion of "halo" "hila" at https://ohr.edu/explore_judais...i/ask_the_rabbi/4101
