We do not currently know of any synonyms for Btss.
The noun Btss is defined as:
Abbreviation for Baronetess, the feminine form of Baronet. It is a post-nominative title; the pre-nominative is Dame (e.g. Dame Jane Smith Btss). A more progressive form is for the holder of the honor to use Bt as a post-nominative (e.g. Dame Jane Smith Bt), as it does not refer to the recipient's gender (though the title "Dame" still does).