The Complete Idiot''s Guide to Music Theory

polyrhythm
Two or more rhythms played simultaneously, or against each other.
polytonality
Employing more than one tonality simultaneously.
prestissimo
Tempo marking for an extremely fast tempo, faster than presto.
presto
Tempo marking for a very fast tempo.
primary chords
The most important chords in a key: I, IV, V.
rallentando
Gradually slow down. (Abbreviated as 
rall.
)
relative keys
Keys that share the same key signature, but not the same root.
For example, A minor and C Major are relative keys.
resolve
The act of moving a suspended note down to a chord tone of the chord.
rest
A symbol used to denote silence or not playing a particular note.
rhythm
The organization of sound in time; the arrangement of beats and
accents in music.
ritardando
Gradually slow down. (Abbreviated as 
rit.
or 
ritard.
)
ritenuto
Hold back the tempo. (Abbreviated as 
riten.
)
Romantic
Music associated with the period from 1820 to 1900, characterized
by emotional musical expression and sophisticated harmonies, often employing
chromaticism and a moving away from traditional tonality. Notable Romantic
composers include Johannes Brahms, Antonin Dvorˇák, Franz Liszt, Felix
Mendelssohn, Richard Strauss, Pyotr Tchaikovsky, and Richard Wagner.
root
The fundamental note in a chord.
SATB
Shorthand for soprano, alto, tenor, and bass. (Choral scores are some-
times called SATB scores.)
scale
A sequence of related pitches, arranged in ascending or descending
order.
score
(1) The written depiction of all the individual parts played of each of
the instruments in an ensemble. (2) To orchestrate a composition.