A vocal/choral composition in which there is little or no repetition in the musical structure i.e. where the composition is not structured as verse/chorus. Some of the best examples of through-composed songs include those from Lied. 'Erlkönig' is through-composed. Listen to the way the singer changes his body language and tone of voice to portray the different characters (narrator, father, son and Erlkönig).
The structure of through-composed songs is not confined to the romantic period, listen to 'Bohemian Rhapsody' by Queen.
Ian Bostridge sings 'Erlkönig'.
An example of a through-composed song structure not confined to the Romantic period.
A detailed explanation of through-composed.