per
prep. A2 Elementary Oxford US //ˈpɝ// UK //pˈɜː// per
prep. for each person, thing, or unit. You use this when talking about prices, speeds, or how much of something you need.
prep. for each; for every. Used to express a ratio or a rate between two units.
The apples cost two dollars per kilogram.
The speed limit on this road is sixty kilometers per hour to ensure pedestrian safety.
The study calculated the average caloric intake per person across several different demographics to determine if local food security had improved over the decade.
Usage
Commonly used in technical, commercial, or mathematical contexts to link two units of measurement.