This is the 5809th most frequent Dutch word.
onderwijl
Meanwhile; in the meantime.
Here, 'onderwijl' is used to indicate that an action (listening to music) is taking place simultaneously with another action (reading a book).
Hij las een boek, onderwijl luisterend naar de muziek.
He read a book while listening to the music.
In this sentence, 'onderwijl' emphasizes the concurrency of activities—working diligently and occasionally looking at the clock.
De leerlingen werkten ijverig, onderwijl kijkend naar de klok.
The students worked diligently while glancing at the clock.
Here, 'onderwijl' functions as 'meanwhile,' indicating that the teacher's action occurred concurrently with other unspecified activities or circumstances.