A person who shares a parent; one's brother or sister who one shares a parent with.
A node in a data structure that shares its parent with another node.
The most closely related species, or one of several most closely related species when none can be determined to be more closely related.
The stepson of one's parent who is not one's half-brother.
The son of one's stepparent who is not the son of either of one's biological parents.