I stand, partially, corrected. I found, in the depths of internets, some chabadniks using the terms “a shaliach and a mekarev” and the like in articles and in section headers. I did not, though, see these words in direct quotes from Rebbeim and Rabbonim. In many cases, mekarev means a less loaded term, as in a close talmid or friend, as in “R X was a mekarev of Gadol Y”. So, the question is whether “kiruv” is a shortcut for “kiruv rechokim” or has a separate meaning. I would err to the side of caution and not offend Yidden.
“kiruv rechokim” deserved an article on the chabad site, with this quote from L Rebbe ZT’L:
You call them “distant”?! What gives you the right to say that you are close and they are far? You must approach each one of them as though you are the King’s servant sent with a message to His most precious child!
Similarly:
One Chabad supporter told the Rebbe about a Shabbaton he had sponsored for over forty couples who “had no Jewish background.”
“No what?” the Rebbe responded, as though in shock.
“No Jewish background,” was the hesitant response.
“Tell them that they have a background! Their background is that they are children of Abraham, Isaac and Jacob!” the Rebbe replied.