This is the 10246th most frequent Polish word.
błędem
"Error" or "mistake."
The word 'błędem' is used here in its instrumental case form to describe an action or decision that is considered erroneous.
Uważam, że to był wielkim błędem.
I think it was a big mistake.
Here, 'błędem' serves as the instrumental case form related to the verb 'być' (to be), explaining a state or condition.
Wskazywanie na innych jako winnych może być błędem.
Pointing at others as guilty can be a mistake.
In this sentence, 'błąd' appears in its basic nominative form as the subject of the phrase.