Sentence:  Of course , it must not be forgotten that in achieving this historical feat , Prokofieff had the vast resources of his people behind him ; time and economic security ; symphony orchestras , <WSD>opera</WSD> and ballet companies ; choruses , chamber music ensembles ; soloists ; recordings ; broadcastings ; television ; large and eager audiences . 
Meaning of the word marked with <WSD> tags:  a drama set to music; consists of singing with orchestral accompaniment and an orchestral overture and interludes