The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
adjective Abbr. mksA
Of or being a system of units using the meter, the kilogram, the second, and the ampere as basic units of length, mass, time, and electric current.