synem

In a sentence

• On jest moim synem.

  He is my son.

  The word 'synem' is used as the instrumental case form of 'syn,' which is used here to indicate the role or identity of the subject in a state of being.

• Mówiłem o moim synem wczoraj.

  I was talking about my son yesterday.

  Here, 'synem' is mistakenly used instead of the correct case for 'about,' which should be the locative case 'synu' when following 'o,' demonstrating an intentional error for discussion.

• Zawsze jestem dumny, gdy widzę mojego synem sukcesy.

  I am always proud when I see my son's successes.

  In this sentence, 'synem' is used to emphasize the relationship with 'mojego,' where 'synem' serves as an incorrect replacement of 'syna' (the accusative case), potentially for highlighting a vernacular nuance.