répétiteur
ré pé ti teur |ˌrāˌpātiˈtər rəˈpɛditər | ▶noun a tutor or coach of ballet dancers or musicians, esp. opera singers. ORIGIN French.
répétiteur |rɛˌpɛtɪˈtəː | ▶noun a tutor or coach of ballet dancers or musicians, especially opera singers. ORIGIN French.