In the early 18th century, the term " symphony " was applied to any instrumental prelude, interlude, or postlude. In modern usage, the term is applied to a large composition for orchestra, generally in three or four movements. The symphony may also be defined as a sonata for orchestra. The earlier symphonies, those of the Classical era, were generally simpler, and of a smaller scale. By the late Romantic era, the symphony had grown in number of movements, length of movements, number of instruments, variety of instruments, and dynamic range.the word literally means 'sounding together'. In the early 18th-century, it meant an instrumental section of a choral work. today, it describes a large-scale orchestral work usually in four movements<br><br>A rather long orchestral composition, divided into three to four movements, or sections.