I. per di ‧ em 1 /pə ˈdiːəm $ pər-/ BrE AmE noun [countable] American English
1 . an amount of money that an employer pays a worker for each day that is worked
2 . an amount of money that a worker is allowed to spend when doing his or her job, for example on a business trip:
a per diem allowance
II. per diem 2 BrE AmE adverb American English formal
[ Date: 1500-1600 ; Language: Latin ; Origin: 'by the day' ]
for each day or on each day:
workers who are paid per diem