UN Security Council: A body within the UN system composed of 15 members who have one vote and have primary responsibility for maintaining international peace and security. UN

UN Women (UNWOMEN): UN Agency for Gender Equality and the Empowerment of Women, which brings together other UN agencies, and leads the Gender Reference Group on Humanitarian Issues. UN WOMEN

Unaccompanied and separated children: Children separated from both parents and other relatives, who are not in the care of an adult who, by law or custom, has such responsibility; or children separated from both parents or from their legal or customary guardians who are not necessarily relatives, and who may therefore be accompanied by other adult family members. IOM

Under-five mortality: Annual number of deaths of children under 5 years of age. For purposes of comparison between countries or across years, it is expressed as a Rate per 1,000 Live Births in a given year. WHO

Underfeeding or undernourishment: The condition of a person whose regular food consumption is insufficient to provide the necessary amount of food energy on a continuous basis. It is synonymous with chronic hunger. FAO

Underground water sources: Water sources that are found below the earth's surface and occupy the pores and fissures of the most solid rocks. GROUNDWATER

Underweight: Low weight-for-age in children and body mass index (BMI) < 18.5 in adults, due to a current situation resulting from insufficient food intake, past episodes of malnutrition, or poor health conditions. WHO

Unemployment: Persons over a certain age allowed to work who are not engaged in any occupation, employment, or independent activity and are looking for work. UNESCO

Uninhabitable housing: Housing that lacks the minimum conditions to be inhabited, since they represent a danger for people. US LEGAL

United Nations (UN): An international organization founded in 1945 whose central objectives are to maintain international peace and security, to centralize and harmonize the efforts of nations to achieve their common interests, and to promote peaceful relations among States. UN

United Nations Children’s Fund (UNICEF): UN agency to help guarantee the rights of children and adolescents, based on the Convention on the Rights of the Child and its Optional Protocols. UNICEF

United Nations Civil-Military Humanitarian Coordination: Support by military actors and resources for the entry, transfer and safeguarding of humanitarian assistance, without prejudice to its civilian nature and guaranteeing the preservation of its purposes. OCHA

United Nations Development Programme (UNDP): UN agency that works to eradicate poverty, protect the planet, and promote peace and justice. UNDP

United Nations Environment Programme (UNEP): UN agency that acts as an advocate, educator, and facilitator on global environmental issues. UNEP

United Nations Habitat Organization (UN-Habitat): United Nations program promoting socially and environmentally sustainable towns and cities. UN HABITAT