base unit

noun Physics.
  1. one of the units, as mass, length, time, or electric current, taken as a basis for a system of units in the sciences.
Also called fundamental unit.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for base unit

base unit

noun
  1. physics any of the fundamental units in a system of measurement. The base SI units are the metre, kilogram, second, ampere, kelvin, candela, and mole
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

base unit in Medicine

base unit

n.
  1. Any of the fundamental units of length, mass, time, electric current, thermodynamic temperature, amount of substance, or luminous intensity in the International System of Units, consisting respectively of the meter, kilogram, second, ampere, kelvin, mole, and candela.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.