Motif
A recurring image, object, phrase, or idea that supports a work’s themes.
A motif gains meaning through repetition, drawing the reader’s attention to patterns that point toward larger themes. Unlike a single symbol, a motif appears again and again, accumulating significance. Writers use motifs to give a work unity and to guide interpretation.
Example
The motif of blood recurs throughout the play, evolving from a mark of courage into an inescapable stain of guilt that cannot be washed away.
Macbeth · William Shakespeare