Kin are your blood relatives: the people you're related to by birth. Your parents, siblings, grandparents, aunts, uncles, and cousins are all your kin.

When someone says “he's kin to me,” they mean they're related by blood. In many cultures, people feel a strong duty to help and protect their kin. You might hear someone say “blood is thicker than water,” meaning family bonds run deep.

The word appears in several common phrases. Your next of kin is your closest living relative, the person who would be contacted in an emergency. Kith and kin is an old-fashioned phrase meaning friends and family (kith means friends or neighbors, though almost nobody uses that word by itself anymore).

People also use kin more broadly to describe a sense of connection. When you feel kinship with someone, you feel close to them, like you're part of the same group or share something important. Scientists talk about kindred species that are closely related through evolution. Two people with similar personalities might be called kindred spirits, even if they're not related by blood at all.