In music, (primarily classical/piano) what do the abbreviations stand for?

Question

And for that matter, enlighten me on what defines something as a Sonata, Rondo, Allegro, etc. I need help with musical linguistics.

Such as in:

Moonlight Sonata Op. 27 No. 2

and

Andante Grazioso Sonata K. 333

and

Impromptu Op. 90 No. 2

Answer 1

I'm not positive what "K." stands for, but "Op." is definetly short for "opus." A sonata is typically a piece that's played instrumentally, as opposed to one that is sung. Rondo is a form of music. It's the basic one that basically goes ABACADA, etc. Allegro simply means fast or quick and lively. It's used as an adjective and is often written above music to instruct the musician on the tempo.

Answer 2

Just to prevent a few more abbreviations from stumping you in the future:

Otto Erich Deutsch catalogued the works of Schubert, so that's what the D stands for.

There are two competing catalogues of the works of Domenico Scarlatti.  The K stands for Kirkpatrick and the L stands for Longo.

The catalogue of the works of Johann Sebastian Bach is called the Bach-Werke-Verzeichnis, so that is what BWV stands for.  One writer tried to change it to S, because he wanted to pay tribute to Schneider, the author of the catalogue.  His effort never took hold, however.

If one work is an adaptation or selection from a larger work, the opus number could be followed by a lower-case letter.  The Nutcracker Ballet is op. 71 and the Nutcracker Suite, which consists of selections from the Nutcracker Ballet, is op. 71a.

Answer 3

Op. is short for 'opus' which is simply the Latin for 'work'. So, Op.90 would be the 90th work in the composer's catalogue. If something like 'No.2' follows then it indicates that the composer wrote more then one work to which he ascribed a group opus number, such as Beethoven's Piano Sonata in C sharp minor (NB Beethoven did NOT call this work the 'Moonlight Sonata' - it was appended later). Op 27 No 1 is Beethoven's Piano Sonata No 13 'Quasi una fantasia' (a title also given to the 'Moonlight' Sonata) in E flat. Beethoven obviously saw these two works as a complementary pair.

The 'K' refers to Ludwig Köchel, who catalogued Mozart's works in the 19th century in what he thought was chronological order. So, the Piano Sonata in B flat (for which you have listed just one movement, strangely) is No 333 in Köchel's catalogue of Mozart's works.

It is interesting to bear in mind that, during the 17th and 18th centuries, opus numbers were often given to a work when it was published. This did not always correspond to the order or date of composition. Some of Beethoven's  works are notorious for having misleadingly high opus numbers simply because they were published some years after they were written.