How does Roald Dahl use metaphor in "Lamb to the Slaughter"?
Roald Dahl uses metaphor to better describe Mary Maloney in his short story "Lamb to the Slaughter."
A metaphor makes a comparison between two things that are unrelated but share some common characteristics. Working with that definition, a simile is a type of metaphor, because it also makes a comparison in the same manner. A simile simply uses "like" or "as" to make the comparison.
The following is a simile from "Lamb to the Slaughter."
She loved to luxuriate in the presence of this man, and to feel – almost as a sunbather feels the sun – that warm male glow that came out of him to her when they were alone together.
Patrick's very presence is equivalent to the life giving solar energy of the sun for Mary. She practically bathes in his glow.
As for a standard metaphor, the title hints at the extended metaphor of the story. Mary is meek and mild like a lamb. When Patrick delivers his awful news, Mary is devastated. In a way, she and her life have been completely slaughtered by Patrick's betrayal. Then Mary, the lamb, brings an actual leg of lamb to a new slaughter. Patrick's slaughter. The lamb has now become the slaughterer.