Why is it called a widow's peak?

The widow's peak resembled a peaked hood that widows would wear when in mourning. Because a widow's peak is a V-shaped hairline that peaks in the middle of the forehead, it evokes those hoods.

The tradition of widows wearing peaked hoods dates back at least to the 16th century, while the term was applied to hairlines in the 19th century. Women with widow's peaks were thought to be fated for early widowhood. Though some claim that whether a person has a widow's peak is controlled by a single dominant gene, there is no documented evidence that this is true, especially because whether someone has a widow's peak at all is fairly subjective.