A composition, for a full orchestra, designed as an introduction to an oratorio, opera, or ballet, or as an independent piece; -- called in the latter case a concert overture.
Derived from the French word overture; the instrumental music which is played before the start of an opera. It was originally a short prelude. but was developed by Lully into a longer piece. In the 19th century it became more complex, often being developed symphonically. A good example is the overture to Verdi 's La Forza del Destino. However many are now played in concerts and some composers are only remembered for their overtures. Not so in the case of Verdi of course.
an instrumental introduction to an opera, oratorio, cantata, suite (or similar instrumental work). C18 overtures were of two distinct styles: Italian and French.