Ciotka (ciocia) and wujek
There is also obsolete (more or less, depending the region of Poland) forms: stryj and stryjenka. BUT
these are not equal to wujek/ciocia.
Wujek is our parent brother, while stryj is our parent sister's husband.
Ciotka is our parent sister, while stryjenka is our parent brother's wife.
In other words: stryj is ciotka's husband, while stryjenka is wujek's wife.