From wikipedia – Link Here
A silhouette is a view of an object or scene consisting of the outline and a featureless interior, with the silhouetted object usually being black. The term was initially applied in the 18th century to portraits or other pictorial representations cut from thin black card.
The term has been extended to describe the sight or image of a person, object or scene that is backlit, and appears dark against a lighter background. Because a silhouette emphasises the outline, the word has also been used in the fields of fashion and fitness to describe the shape of a person's body or the shape created by wearing clothing of a particular style or period.
Hongkiat again, This time posted 85 Free High Quality Silhouette Sets. Just showing some examples here
1. People
2. Animals
3. Birds
4. Butterflies
5. Bugs
6. Sea creatures
7. Plants
8. Sports
9. Aircraft
10. Buildings
For more and to download check this post