consonance
A combination of notes that sounds stable and pleasing.
In Depth
Consonant intervals and chords sound stable and resolved to most listeners. Perfect consonances — the unison, octave, perfect fifth, and perfect fourth — are the most stable. Imperfect consonances — major and minor thirds and sixths — sound pleasant but with more warmth and colour.
The perception of consonance has evolved over the centuries. In medieval music, only perfect consonances were considered acceptable. The Renaissance embraced thirds and sixths as consonant. Today, jazz musicians treat seventh chords as stable, while classical theory still classifies them as dissonances requiring resolution. What sounds consonant is partly cultural and partly acoustic.
In the Middle Ages, the interval of a third was considered dissonant and unsuitable for church music. Today it is the foundation of every major and minor chord.