Definition of "per" []

• To, for, or by each; for every: Gasoline once cost 40 cents per gallon. (preposition)
• According to; by: Changes were made to the manuscript per the author's instructions. (preposition)
• By means of; through. (preposition)
• Informal For each one; apiece: sold the cookies for one dollar per. (adverb)
• Informal Per hour: was driving at 60 miles per. (adverb)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Kilwardby also stresses that in a per se necessity sentence, the subject must be ˜something belonging in itself to that predicate™ (˜per se aliquod ipsius predicati™), by which he seems to mean that the subject has the predicate as an essential property, i.e., such that it has the predicate as a necessary property through itself and not through something else."
• "Copper prices have since risen from less than US$1 per pound to more than US$3 per pound (about �per kilogram), driven in large part by growing demand from China."
• "Why attacks on humans were measured in millions per incident instead of the standard #-per 100,000 people-per year?"