This is the 7960th most frequent Polish word.
myślą
"Myślą" means "they think" or "by thinking" in English, depending on the context.
In this sentence, "myślą" is used as the third person plural of the verb "myśleć," meaning "to think."
Oni myślą o przyszłości.
They are thinking about the future.
Here, "myślą" functions as the instrumental case singular form of the noun "myśl," meaning "thought."
Samotnie siedział, pogrążony w myślą.
He sat alone, immersed in thought.
In this sentence, "myślą" is again the instrumental case singular form of the noun "myśl," demonstrating a quality or attribute affiliated with thinking.