To state the blindingly obvious a cadenza is the segment in a concerto when all the other instruments stop playing while the soloist(s) gets a chance to show off, developing the themes from the movement and accentuating areas in which their technique is at its best.
My only problem with the definition is how short is too short to be a cadenza.
In our prelim listening there was half a bar where the solo instrument was playing alone and showing off with what sounded like demi-semis. The teacher said that this was to short to be a cadenza yet in the concertos i have heard and all the definitions i have read there has never been a minimum or maximum length for a cadenza.
So i thought i would ask the collective view on how long a cadenza has to be to be a cadenza?
and on another point from the same question how could Basso Continuo be correct when the bass stopped for half a bar?

Half a bar does seem to be far too short for a cadenza - it's more like a couple of beats where the soloist happens to be playing while nobody else is.

Having said that, I couldn't say that it was too short to be a cadenza by a measurable amount. In fact I've never heard the question being raised before and I doubt that anyone else has either. My general feeling would be that during a cadenza the orchestra "downs tools" while the soloist tootles along for a bit, effectively playing "out of time" with the rest of the piece.

Of course there are exceptions. The Schumann Piano Concerto (in fact most piano concertos, but this is the one that comes to mind) has a cadenza lasting a definite number of bars and doesn't feel "out of time" at all. Rhapsody In Blue has a long piano solo which does not, however, "feel" like a cadenza. And the second movement of the Berg Violin Concerto starts with a cadenza which has full orchestral accompaniment!

So, no straight answer from here, I'm afraid. But I still say that half a bar of solo ain't no cadenza.

The shortest thing I've heard referred to as a cadenza was a clarinet solo in Suppe's Light Cavalry Overture - however, it is marked as bars rest rather than a pause so it may have just been the way my conductor chose to refer to it. It's definitely in cadenza style, though - an beautiful unaccompanied lyrical bit of clarinet.

Half a bar pretty much definitely wouldn't be considered a cadenza (even if it technically was one), but a cadenza-like Eingang consisting of 3 or 4 bars of solo Horn appears a few times as a transition in the Mozart Horn Concerti.

According to my Oxford Dictionary of Music...
"....the orchestra joins in again only when the soloist, after a display of vocal or instrumental virtuosity, indicates by a long trill that he or she is ready to be rejoined in the final chords or in any passage elaborated out of them..." The "final chords" being those leading to a perfect cadence.

Cadenzas are usually played at the end of a piece, but, Beethoven being who he was, actually opens the first movement of the Piano Concerto No 5 with a cadenza which takes up the first 14 bars. Something which caused quite a stir in it's time!

Thanks for your views on it.
What do you make of the Basso continuo bit? I had always thought that if it stopped, for however brief a period, it by definition couldn't be a basso continuo.

The point of the basso continuo is that it is figured bass. If there are no figures, then the bass would rest. The "continued bass" is a literal translation and doesn't necessarily mean the bass is playing all the way through the piece.

Hope this makes sense!

According to the New Grove Dictionary of Music and Musicians

'the term ‘cadenza’ can refer to simple ornaments on the penultimate note of a cadence, or to any accumulation of elaborate embellishments inserted near the end of a section or at fermata points'.

Wouldn't the New Grove definition contradict the Oxford definition then?
It seems that in the New Grove there isn't even a mention of a trill which the Oxford says that it is obligatory.
Thanks for clarifying the Basso Continuo bit appleblossom, i just wish music would stick to literal translations once in a while .

I guess a literal translation of Cadenza would be cadence, wouldn't it? So I suppose a less prescriptive definition may be more accurate?

I agree with that, but also consider it consistent with the practice of the later masters. Trills were common in cadenzas, but I think many Romantic composers would have been happy to leave them out if something else had fitted the rest of the movement better.

The first movement cadenza of the Mendelssohn Violin Concerto has trills within it, but after them there are 25 bars containing string-crossing arpeggios for the solist. Bars 11, 12, 13 and 14 of this sequence are an 864, a 743, an 853 and another 864, respectively, all on the dominant [B]; the orchestra enters in the middle of 13, and the actual cadence is produced by an E on the orchestral basses at the beginning of 14.

The essential cadential nature of this solo passage is in the arpeggios and very remote from the trills.

Yes that is correct.

The term cadenza was first used to describe the embellishment of an ending in about 1520-1530. The cadenza developed over time. In Baroque music a cadenza can be quite simple. In 1771 Tartini published rules for constructing cadenzas which did mention the cadenza ending on a trill. So you could say that both definitions are correct, but that the New Grove definition is broader as it can be applied to early cadenzas as well as later ones.