underscore
n. B2 Upper Intermediate US //ˌəndɝˈskɔɹ// UK //ˌʌndəskˈɔː// un·der·score
n. a short line under a note in music that tells you to play it slightly louder than the notes around it. It is often used to emphasize a specific sound.
n. a short line placed beneath a musical note to indicate a slight increase in volume or intensity. It is a standard marking in various musical notations to highlight specific passages.
The composer used an underscore to make the final note stand out.
When the choir reached the chorus, the conductor marked the lead singer's line with an underscore to ensure the audience heard the high note.
The arranger added an underscore to the final chord of the movement, creating a dramatic swell that signaled the transition to the next section.
From under- + score.