Ternary Form
A three-part form whose opening returns complete after a contrasting middle
Related
Ternary form is A–B–A: a section is stated, a contrasting section follows, and the opening returns complete. The return normally stays in the tonic, and clear boundaries give the shape its symmetry. The minuet–trio–minuet pattern is the standard case, the da capo mark bringing the dance back.
The middle usually moves to a related, subdominant or parallel key and changes character, texture and register, so the return has something to resolve. If the return is shortened to its opening phrase, or B and A share material, the result sits between ternary and rounded binary.
The test is a complete return. A single recalled phrase that leads to the close is binary; a return that develops further leans toward rondo or sonata form. Memorise how A closes, then hear whether it closes the same way again.
Sources
- 三部曲式的结构、对比段与再现写法，参 The New Grove Dictionary of Music and Musicians, "Ternary form"；本文为原创表述
Used for fact-checking only; all prose is original.