A dark shape or outline of a person or object that appears against a lighter background, especially one that is visible against a light or a brightly lit background.
Here are some other ways to define silhouette:
* The outline or shape of something, especially a person's head or body.
* A picture or drawing of something in outline, especially in black.
* A style of painting or drawing in which subjects are shown as dark shapes against a light background.
The word silhouette comes from the French "silhouette", which in turn comes from Étienne de Silhouette, a French minister of finance in the 18th century who was known for his frugal lifestyle. His name became associated with cheap, outline-style portraits, because they were much cheaper than full-color portraits.