I think part of the issue with the question is that the terms "holy" and "sacred" are not clearly enough defined in distinctly different ways.
On the Wikipedia page, there appears the following distinction:
Holiness is generally the term used in relation to persons and
relationship, whereas sacredness is used in relation to objects,
places, or happenings.
A couple of lines later, the same Wikipedia page quotes a different source saying:
While both words denote something or someone set apart to the worship
of God and therefore worthy of respect and in some cases veneration,
holy (the stronger word) implies an inherent or essential character.
This seems to imply that the difference is whether the holiness is intrinsic or just imposed from the outside; seemingly this disagrees with the first explanation.
Then, I found the following here:
Holiness is a concept, a virtue that is inside a person or a thing. It
is because of this virtue that he is called or referred to as holy.
Thus, you consider a saint as holy, but he is not sacred to you.
However, there are things that are both holy and sacred such as the
holy bible. Sacred is a word used to distinguish worldly things and
concepts from those that are godly or in some way connected with god.
In general, holy is more of an abstract concept whereas concrete
objects are considered sacred.
Then I came across this answer here on the English stack Exchange:
Whenever you have two Modern English words that mean almost exactly
the same thing, it is probable that only one existed in Old English,
while the other was imported from the Romance languages, there having
been several such bulk imports in English's history. This appears to
be the situation with holy and sacred: the former is Old English, the
latter comes from Latin sacer by way of French sacre and the oldest
citation in the OED is 1380 (referring specifically to the Eucharist)
(He then quotes the Oxford English Dictionary which basically implies this is correct.)
The practical upshot of this is that it's not clear at all what the difference between holy and sacred is, if at all.
It either has to do with what sort of noun is being described (animate vs. inanimate), or being an intrinsic or extrinsic quality, or being "godly" vs being set aside for god, or perhaps there is no difference at all!
Since there does not seem to be a clear-cut distinction between the words, it does not bother me that the root ק-ד-ש accounts for them all.
i did find one other distinction drawn here, and this does find a parallel in Hebrew.
In my understanding, as you pointed out, these days one can say sacred
not necessarily in religious context but also figuratively when
something is really important to somebody, as if it had been sacred in
the traditional sense. e.g. His extensive collection of 60s rock
records is sacred to him. On the other hand holy is specifically used
in relation to God, gods or transcendence, and it has rather strong
Christian connotations to be more specific. Correct me on it if I had
a major misunderstanding about it, if you please
According to this explanation, sacred just means dedicated and special for, without a reference to G-d. Holy, however, always applies to G-d.
This is also the 4th definition listed here.
This does have a parallel in Hebrew. The root ק-ד-ש does have different connotations depending if it is in the פיעל or הפעיל form.
The word מַקְדִיש (makdish) always refers to dedicating an item to G-d and the Beis HaMikdosh- making it holy. The word מְקַדֵש (mikadesh) refers to designating something and making it set aside, unique, without it becoming the property of G-d or the Beis HaMikdosh.
Thus when a man betroths a woman, he is מקדש אותה mikadesh otah. When a man designates an animal to become a korban/sacrifice in the Beis HaMikdash, he is מקדיש makdish the animal.
In summation: The terms "holy" and "sacred" are not so clearly defined enough as to really be different words, so that having one Hebrew word is adequate. It could be that there is no difference at all between holy and sacred. And according to one definition which does make a distinction between the words, we found that Hebrew does indeed account for the difference in terms.
