Micro,”In the metric system it means 1/million. (ex.: Microgram = 1/1,000 June 23, 2017 mfadmin Pharmacy Average Rating 0 out of 5 stars. 0 votes.You must log in to submit a review. Micro,”In the metric system it means 1/million. (ex.: Microgram = 1/1,000 000 of a Gram)”