Kinswoman
/ˈkɪnzwɪmɪn/
Definition 1 of 1
Pro Tip 1/3Gender Specific
Kinswoman refers only to female relatives, not male ones. 
My uncle's wife is also considered my kinswoman.
Pro Tip 2/3Direct and Indirect
Kinswoman can include both direct relations like sisters and indirect ones like cousins. 
My father's cousin is still my kinswoman, even though we're not closely related.
Pro Tip 3/3Historical Use
Kinswoman might sound old-fashioned; modern English often prefers 'female relative'. 
In historical novels, you'll often find the term kinswoman used frequently.