also R.E.M., rem, unit for measuring ionizing radiation, 1947, acronym of roentgen equivalent man.
As "twigs of broom tied together to a handle to make a tool for sweeping," mid-14c. Traditionally, both the flowers and sweeping with broom twigs were considered unlucky in May (Suffolk, Sussex, Wiltshire, etc.).
standard commercial measure of paper, rem, mid-14c., from Old French reyme, from Spanish resma, from Arabic rizmah "bundle" (of paper), from rasama "collect into a bundle." The Moors brought manufacture of cotton paper to Spain.
The exact path of transmission of the word to English is unclear, and it might have entered from more than one language. An early variant rym (late 15c.) suggests a Dutch influence: compare Middle Dutch rieme, Dutch riem, which probably were borrowed from Spanish during the Hapsburg control of Holland. For ordinary writing paper, 20 quires of 24 sheets each, or 480 sheets; often 500 or more to allow for waste; the count varies slightly for drawing or printing paper.