Whats the definition of structure in music terms?

Structure is the way the component part or elements of a musical creation are organized. Elements that can be shaped within a musical structure include phrases, chords, melodies, sections of a song, themes or motifs throughout a movement or composition.

For example, the twelve bar blues progression is a very common structural technique found in the genre of the blues that consists of two phrases that each is four bars long and a phrase that takes up two bars.