Jabà Âonkowanie () or siakanie () is a regional phonological feature of the Polish language. It consists of the merger of the series of retroflex sibilants and palatal sibilants into a phonetically-intermediate series , , , (sometimes written ).
It is named after the of Polish (named after the town of Jabà Âonków in Cieszyn Silesia). It occurs in a number of other Polish subdialects.
The feature is linked to the process of dispalatalization (reducing of the number of palatalized consonants) similar to the phenomena of and ' in other dialects.