See also lists of all IFRC regions, National Societies, and Country codes
: OA : Operational Alliances
: OAG : Opposition Armed Group
: OCDE : Organisation de coopération et de développement économiques
: OCHA : Office for the Coordination of Humanitarian Affairs
: OCV : Oral Cholera Vaccine
: OD : Organisational Development
: ODA : Overseas Development Assistance
: OECD : the Organisation for Economic Co-operation and Development
: OFDA : Office of U.S. Foreign Disaster Assistance
: OHCHR : Office of the High Commissioner for Human Rights
: OIC : Organisation of Islamic Cooperation
: OIE : World Organisation for Animal Health
: OM : Operational manual
: One Health : A concept recognising the interaction between humans, animals and the environment as a prerequisite for understanding and managing global health threats
: One WASH : A new “game-changing” financing mechanism to end cholera launched at UN General Assembly September 2019
: OneWash : Same as One Wash
: OPT : Occupied Palestinian Territory
: ORP : Oral Rehydration Points
: ORS : Oral Rehydration Solution _ Oral Rehydration Salt (or salts)
: ORT : Oral Rehydration Therapy
: OST : Opioid substitution therapy
: OSV : Other situations of violence
: OTP : Outpatient Therapeutic Programme
: OVC : Orphans and Vulnerable Children