Camel toe, or cameltoe, is slang for when the outline of a woman's labia majora is seen in tightly fitting clothes. The male equivalent of cameltoe is mooseknuckle or manbulge. It is called a "camel toe" because of how the woman's labia outline is similar to that of a camel's toe.
Camel toe happens as a result of wearing tight-fitting clothes, such as shorts, leggings or swimwear.
... let's just say the words 'crotch outline' and let that suffice.
Cameltoe is slang for a fashion faux pas caused by women wearing snug pants; the term suggests a visual analogy.