per

Từ điển American Heritage Dictionary 4th

per (pûr)prep.
1. To, for, or by each; for every:
Gasoline once cost 40 cents per gallon.
2. According to; by:
Changes were made to the manuscript per the author's instructions.
3. By means of; through.adv. Informal
1. For each one; apiece:
sold the cookies for one dollar per.
2. Per hour:
was driving at 60 miles per. [Latin. See per¹ in Indo-European Roots.]