What Is a Step Cousin?
If one's aunt or uncle marries someone who already has children from a previous relationship, those children are one's step cousins. While the term "step cousin" is not considered an official relationship under civil law, it is a convenient term to describe such a cousin.
The designation of "step cousin" can be too distant or confusing for some, which is why in some families it is common for extended relatives beyond immediate siblings and first cousins to be referred to as cousins. Moreover, in genealogy research, some individuals refer to close friends of the family as aunts, uncles and cousins despite the fact that they share no familial blood.