Gender non-conforming is an adjective describing any person, thoughts, or behaviors that do not match society’s common expectations concerning masculinity or femininity.
People who are not cisgender are commonly described using this term. However, some cisgender people may also be gender non-conforming to some degree if they express their gender identity in atypical ways. Similarly, people who are not cisgender will not necessarily be described as gender non-conforming if they are not open about their gender identity.
More About Gender Non-Conforming
There are many different ways to be gender non-conforming. People may dress in ways that are atypical for their gender, as men that wear dresses do. They may refer to themselves using pronouns usually used for a different or neutral gender and hope others do the same. They may seek gender reassignment surgery. They may do all these things, some of these things, or other things that put them outside the "norm" for gender expression.
Some people who are gender non-conforming were born male but have more feminine gender expression. Others were born female but have more masculine gender expression. These people may identify as transgender or cisgender, depending on whether their gender identity matches their gender expression. However, these binary options are not the only ones. Some gender non-conforming people sometimes express in a more masculine way sometimes and a more feminine way at other times. Others prefer a more neutral, androgynous gender expression which is neither male nor female.
A person of any sexuality may identify as gender non-conforming. A woman who wears her hair short, prefers pants and shirts over dresses, and does not wear makeup may identify as a gender non-conforming “butch” lesbian, for example, or simply be a straight woman who prefers a more masculine style. Children may also be called non-conforming. For example, a gender non-conforming boy may prefer playing with dolls over cars and enjoy having his nails painted. While societal's gender norms are shifting, they are still quite rigid in terms of which behaviors are considered masculine and feminine.
Being gender-nonconforming can be very freeing as people can feel they are living in the most authentic way. However, it can also be very isolating, especially if gender-nonconforming people are not supported or understood. Gender-nonconforming people are more likely to be abused and isolated for their inability to conform to gender norms. While societal's gender norms are shifting, they are still quite rigid in terms of which behaviors are considered masculine and feminine.