This is the 503rd most frequent Polish word.
tymczasem
"Meanwhile" or "in the meantime."
The word 'tymczasem' is used here to indicate an action taking place at the same time as another event, emphasizing the simultaneity.
Tymczasem przygotowałem obiad dla wszystkich.
Meanwhile, I prepared lunch for everyone.
Here, 'tymczasem' serves to transition between describing one action and the ensuing opportunity that arises concurrently, highlighting contrast.
Dzieci poszły się bawić, tymczasem dorośli mogli porozmawiać na spokojnie.
The children went to play; meanwhile, the adults could talk calmly.
In this context, 'tymczasem' draws attention to a parallel and contrasting development occurring during the same timeframe.