backupsinging

noun
UK /ˈbækʌpˌsɪŋɪŋ/
US /ˈbækʌpˌsɪŋɪŋ/

Singing along with someone to help them sound better.

The little girl did backup singing for her brother at the school show.


OTHER MEANINGS

2. The job of a singer who supports the main singer.

She got a backup singing gig on a big tour.

3. Recorded vocals used to support a live performance.

The band used backup singing on the chorus.

4. The act of singing softly behind someone to give them confidence.

His friends did backup singing so he wouldn't feel nervous.