R
rallentando - gradually getting slower.

range - the pitch distance between the highest and lowest note of a melody, voice, or instrument.

rapidamente - rapidly.

rattenuto - holding back.

realization, to realize - filling in the harmony of a figured bass.

recitative - a declamatory prose style of singing in operas, oratorios, and cantatas.

refrain - recurrent lines of text and music at the end of each stanza of a song.

register - the general pitch level of a part, voice, or instrument (e.g., soprano implies a high register, bass a low register).

registration - the combinations of stops used in an organ composition.

relative keys - major and minor keys which have the same key signature (e.g., C major and A minor are relative keys).

religioso - solemnly, in a devout manner.

replicazione - repetition.

requiem - a Mass for the Dead, set to music for solo voices and chores.

responsorial - in plainsong, a section for solo voice followed by a section for chorus in unison.

rhapsody - a free fantasy, usually of heroic or national character, and often brilliant in style.

rhumba (rumba) - a Cuban dance with complex rhythm, much syncopation, and repetition of an eight-bar theme.

rhythm - the time element in music which is determined by accent and/or duration of tones.

rigaudon (English: rigadoon) - a seventeenth century Provenqal dance in lively duple or quadruple time. Something like a Bourrée, with the phrases beginning on the last quarter of the bar.

rigore - strictness.

rinforzando - reinforced rinforzando

ripetizione - repetition.

risoluto - bold, resolved.

ritardando - gradually getting slower.

ritenuto - suddenly slower, held back.

romance - a piece that is song-like, sentimental and tender in character.

rondino - a small or easy rondo.

rondo - French 'rondeau' a piece in which the main theme keeps recurring with different episodes between - ABACA. A more modern form is extended to ABACAB and coda.

root - the tone on which a chord is built.

rubato - robbed, taking a portion of time from one note and giving it to another.

rustico - rural, rustic.