What is... Rubato?

Rubato – or its full name tempo rubato, which literally means 'robbed time' – is the temporary abandonment of strict tempo. It allows the performer to be more flexible with their pace, and they can speed up or slow down to create effect and emphasise certain musical passages.

Spend any time with a group of piano afficionados and chances are somebody will introduce the word 'rubato'. It's one of those specialist terms that's usually pronounced with a certain emphasis: a tone of voice suggesting the speaker has privileged access to a rarefied and exclusive domain of thought. Implication: if you know what rubato is, you're a true connoisseur; and if you don't...

Of course you can head straight for one of the more accessible music dictionaries. But here we run into the enduring problem with so many musical terms: the definition sounds so abstract it's hard to connect it with anything you can actually remember hearing.

In Italian, Rubato - or to give it in full, Tempo rubato - means 'robbed time'. But isn't that what all music does - take us out of our normal experience of the passing of time and slow it down, speed it up or even apparently suspend it altogether?

To make matters worse, the meaning of Rubato appears to have shifted. For Chopin in the early 19th century, and perhaps also for Mozart half a century earlier, the effect wasn't so much tempo 'robbed' as 'skewed'. From what we can gather from contemporary accounts, when Chopin or Mozart played melodic passages, they liked to hold the tempo fairly steady in the left hand, while bending it, stretching it or nudging it forward in the right.

If that seems counter-intuitive, think of a great jazz soloists, say Miles Davis, giving his take on a popular tune. The drums and the bass keep a steady pulse, but Davis's solo floats ecstatically free above it, lingering here, then scurrying to a crucial note ahead of the bass a moment later.

Evidence suggests that it was Liszt who brought us closer to the modern concept of rubato. Now it isn't just in the melody that time is concertina-ed. Both hands delay affectionately here, or press ahead impatently there: it's the basic pulse itself that's toyed with. Used sensitively it's an internsely poetic effect; overused it can be ghastly - think of Peter Sellers giving the lyrics of The Beatles' A Hard Day's Night the full ham-Shakespearian treatment...

The use of rubato may be so subtle we barely notice it. But without it? Well, get a computer-savvy type to input a phrase of Mozart, Chopin or Liszt into a music-writing programme and then run the playback facility. You'll soon notice when it's not there.

This article was first published in the January 2011 issue of BBC Music Magazine