tempo rubato
Flexible tempo where notes are slightly lengthened or shortened for expression.
In Depth
Tempo rubato — literally stolen time — is the practice of expressively bending the tempo by lingering on some notes and hurrying through others. The total time roughly balances out: what is stolen from one beat is returned to another, maintaining the overall pace while adding expressive freedom.
Rubato is essential to Romantic piano music, particularly Chopin, whose rubato was famously subtle and natural. The concept exists on a spectrum: in Baroque and Classical music, rubato is subtle and localised; in Romantic music, it becomes broader and more dramatic. Too much rubato sounds self-indulgent; too little sounds rigid. Finding the right balance is one of the most personal aspects of musical interpretation.
Chopin's rubato was so subtle that different students reported completely contradictory descriptions of how he played — some said he barely deviated from strict time, others said he was completely free.