In Polish names end in
-ski
See in Russian and Belarussian the standard endings for adjectives are long, like doubled:
новый
новая
новое
новые
In Ukrainian you can write them long, but the standard form is short, but the long form is retained in the masculine:
новий
нова
нове
нові
In the other slavonic languages they have short endings:
E.g. in Serbian, the adjective Serbian is Српски, Српска
In Polish the names end in
-ski or -ska (m/f).
Thus Mr. Kaczyński is married to Mrs. Kaczyńska.
But when Polish names are transliterated into Russian, they Russify them to:
Качиньский , Качинськая. If you see something written about the Polish president, Lech Kaczyński, in a Russian newspaper they'll put -ский at the end even though in Polish it ends -ski. (Лех Качиньский)
This means the names will decline:
Дом Качиньского - Mr. Kaczyński's house
Of course in Polish the name would decline in the same way:
Dom Kaczyńskego