| EFF | Efficiency | 效率 |
| EFF | Electronic Frontier Foundation | 电子前线基金会 |
| EFF | Earth Federation Forces (Mobile Suit Gundam anime) | 地球联邦部队（机动装Gundam动漫） |
| EFF | Enhanced Formation Flying | 增强编队飞行 |
| EFF | Extended Fund Facility (IMF) | 扩展基金贷款（IMF） |
| EFF | Emergency Firefighter (wildland firefighting) | 应急消防员（野外消防） |
| EFF | Evergreen Freedom Foundation | 长青自由基金会 |
| EFF | Experimental Forecast Facility | 实验预测设施 |
| EFF | Extended Financing Facility (International Monetary Fund) | 扩展融资机制（国际货币基金组织） |
| EFF | Extended Format File | 扩展格式文件 |
| EFF | Emulated First-Fit | 模拟首次拟合 |
| EFF | Effingham | 埃芬厄姆 |
| EFF | Equipped For the Future | 为未来做好准备 |
| EFF | Effects | 影响 |
| EFF | Education Freedom Fighter | 教育自由斗士 |
| EFF | Electronic Font Foundry | 电子字体铸造 |
| EFF | Excess Frequency Factor | 过量频率因数 |
| EFF | EsmÉe Fairbairn Foundation (UK charitable trust) | EsmÉe Fairbairn Foundation (UK charitable trust) |
| EFF | Extended Font Format | 扩展字体格式 |
| EFF | Electronic Flight Folder (avionics) | 电子飞行文件夹（航空电子设备） |
| EFF | European Fisheries Fund (EU structural policy) | 欧洲渔业基金（欧盟结构政策） |
| EFF | Equalized Frequency Flow | 均衡频率流量 |
| EFF | Effect(ive) | 效果（ive） |
| EFF | Electronic Font Foundry (Company) | 电子字体铸造（公司） |
| EFF | Escuela de FormaciÓn de Formadores (Spanish, Catholic youth group, Guatemala) | Escuela de FormaciÓn de Formadores (Spanish, Catholic youth group, Guatemala) |
| EFF | Earth Forever Foundation (Bulgaria) | 永久地球基金会（保加利亚） |
| EFF | Essential Function Failure | 基本功能故障 |