Yes it is...But when Catholics do not ask Mary or the Saints to pray for them but instead pray to them to ask them to provide grace, salvation, lost keys and the myriad of other things that these former live in the flesh people are attributed to have power over, it is not intercessory prayer...
As near as I can tell, a pray thee or a pray you is a request, but a pray to is worship...
That's an interesting distinction you're making there, Iscool --- and I like people who can and will think "under the surface" enough to make distinctions, so thank you.
I would say that ordinarily "part" of to "pray to" is worship, because ordinarily we "pray to" AND worship God. (Yes, even Catholics!)
However, that is only "part". As you know, there are general categories for prayer. One can be expressing
If you will review the list above, you will see that all those aspects of prayer can legitimately be expressed to another human being. Me to you, or you to me, for instance. I could express contrition for having treated you badly, thanksgiving that you had done something kind for me, complaint that you had neglected me, or whatever. That is, every one of them is a proper part of our relationship with fellow creatures, except adoration, properly so called.
By "adoration," I mean offering the whole of oneself in homage, as to a Supreme King, giving one's willng and total subjection as to one's Creator and Master, giving the highest, total and unreserved worship as to the Supreme Being.
It is forbidden to give adoration to any creature, whether animal or human or angel.
Nor can one even give those other things (Contrition, Thanksgiving, Request, etc.) to a creature in a total or supreme sense. I can thank YOU for giving me something good, but not without realizing that GOD is the source of ALL good -- in the ultimate sense.
Thus "pray to" is not synonymous with "adoration"; keeping that in mind will prevent many a misunderstanding.
Prayer means worship when it expresses our ucomplete subjection to the Lord of All; it is wrong to offer adoration to any creature.
For Biblical examples of properly addressing angels --- please see also this post: (LINK)
Thank you, Iscool.