“Holy” means “set apart.” I don’t think that’s a proper translation, as “sacred” and “holy” aren’t complete synonyms.
No, “holy,” is related to “whole,” and comes from Germanic roots meaning “entire,” “undivided,” “inviolable”; it’s also related to “hale,” “heal,” “health,” and, for that matter, “halibut.”
There’s a better case to be made for “sacred.” The Latin
sacer (related to Greek σάος, safe), means about what our “sacred” does, and there are varying theories about its ultimate Indo-European roots. One theory connects it to a PIE root *
saq-, “bind, enclose,” implying a covenant or contract. I have seen connections with Hittite
saklai-, “rite, custom,” and another theory that connects it with a root **sek-*, meaning “cut,” so as to imply something cut off (as from ordinary life).
So “holy” does not mean “set apart” in any way, and in fact the word directly suggests the precise opposite. “Sacred” may or may not come in part from a deep, Proto-Indo-European root implying “cut off,” or else from one meaning “bound,” though it does not carry either connotation in Latin. In any event, our word “sacred” does not
mean “set apart” in any literal or reasonably accessible etymological sense, so at most that leaves you with a figurative sense in which it might. Even so, that probably has more to do with the practical fact that things were set apart because they were considered sacred (in the sense of holy), and not called
sacer because they had been set apart.
I’ve heard the claim repeatedly that “sacred means set apart” – generally to support a normative claim that sacred things
should be set apart – and it always struck me as likely to be wrong from a Latin standpoint, which is why I bothered to investigate. Interesting.
Edited to add: I should have noted also that Latin
sacer also has a negative sense meaning “accursed, detestable, damned.”
