Proper noun
IEF
(philately, overprint on stamps) Initialism of Indian Expeditionary Forces.
At the IEF meeting, India and China agreed to join hands to have a collective bargaining power against cartelisation of oil producers. Source: Internet
The IEF (International Energy Forum) has 87 member countries, which account for 90% of oil and Gas supply and demand, just one home for the practice of Energy diplomacy. Source: Internet
Physics of Plasmas 2: 146. "Inertial electrostatic fusion (IEF): A clean energy future" (Microsoft Word document). Source: Internet