>Her original name was Marta Skavronska (a Livonian/Latvian version
of what is certainly a Polish surname).
I've read the authenticity of this name is disputed, so I preferred
not to mention it.
>Presumably an adaptation of Greek Aikaterine was found suitable for
her -- there _is_ a saint with that name -- St. Catherine of Sinai is
worshipped as Aikaterine in the Greek Orthodox Church, AFAIK.
Vasmer writes that <Jekaterina> was probably first mentioned in the
middle of the 15th c. in a description of a pilgrimage to Jerusalem.
Considering the fact that I can't find any traces of this name in Old
and Middle Russian sources, the name most likely was used in relation
to St. Catherine (Gr. Aikateri'ne:) of Alexandria (her 'full
designation' in orthodox tradition , = St. Catherine of Sinai) in
that source. Most likely this name was a bookish exotic one for the
Russians up to the 18th c. It's characteristic that St. Catherine of
Alexandria is _the only_ Catherine in the orthodox church calendar
(in contrast to more that a dozen in the catholic one).
As for Greek Aikateri'ne: < aei` kathari'na 'always pure', Vasmer
refers as far back as to Pape's Wo"rterbuch der griechischen
Eigennamen (1863-1870), where, I suppose, this rather non-standard
development is explained.
Sergei