Finic is a term for people on the multisexual spectrum who have a preference towards people who are feminine in nature (FIN). This can refer to people who are attracted to feminine genders. It can refer to people who are attracted to a feminine gender presentation (regardless of the person's actual gender).
The term can be used by anyone who is attracted to two or more genders but has a preference for femininity. It can be used a sexuality by itself or as a modifier for another sexuality (ie: finic bisexual).