per

Từ điển Oxford Advanced Learner 8th

per BrE [pə(r)] NAmE [pər] BrE strong form [pɜː(r)] AmE strong form [pɜːr] preposition
used to express the cost or amount of sth for each person, number used, distance travelled, etc.
• Rooms cost £50 per person, per night.
•60 miles per hour
• This country has a higher crime rate per 100 000 of the population than most other European countries.
Idioms: ↑as per something ▪ ↑as per usual

Word Origin:
[per] Latin, through, by means of; partly via Old French.