/ɛf/ or /ɛf/ (EF or ef)

Definitions

1. noun

a unit of efficiency, especially in an industrial context, equal to 0.00001 or one ten-thousandth of a unit of power.

“The factory’s overall eff increased by 20% after implementing new energy-efficient machinery.”

2. interjection

used to express effort or energy, especially when making a physical effort.

“Come on, eff! Let’s lift that heavy box together!”