From wstawić +‎ -ka.

• IPA^(key): /ˈfstaf.ka/

• Audio:

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• Rhymes: -afka
• Syllabification: wstaw‧ka

wstawka f

1. insert, insertion (something inserted)
2. inset (smaller image set within a larger one)
3. midpiece (part of a spermatozoon between the head and the tail)
4. (music, opera) intermezzo (short piece of music or act in the interval of the main spectacle)

   Synonyms: interludium, intermedium, intermezzo

• wstawka in Wielki słownik języka polskiego, Instytut Języka Polskiego PAN
• wstawka in Polish dictionaries at PWN