chorus

(n.) An audio effect created by the simultaneous production of tones at slightly different frequencies, resulting in a shimmering sound in the upper overtones. A violin section playing in unison creates a characteristic natural chorus effect.

harmonic

(n.) A tone whose frequency is a multiple of the lowest tone in the harmonic series, the fundamental. Musical sounds consist of a fundamental and a number of harmonic overtones. The exception to this is the sine wave, which is devoid of harmonics.

score

1. (n.) The written notation that represents a musical composition. 2. (v.) To write a musical composition.

semitone

(n.) A musical interval equal to a half step. An octave is made up of 12 consecutive semitones.