Transgender people have a gender identity or gender expression that differs from their sex assigned at birth. Some transgender people who desire medical assistance to transition from one sex to another identify as transsexual. Transgender, often shortened as trans, is also an umbrella term: in addition to including people whose gender identity is the opposite of their assigned sex (trans men and trans women), it may include people who are not exclusively masculine or feminine (people who are non-binary or genderqueer, including bigender, pangender, genderfluid, or agender). Other definitions of transgender also include people who belong to a third gender, or else conceptualize transgender people as a third gender. The term transgender may be defined very broadly to include cross-dressers.