one of a set of unrelated units that form the basis of a system of units. For example, the metre, kilogram, and second are fundamental units of the SI system
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
How to use fundamental unit in a sentence
It had made the family the fundamental unit of the tribe, the clan, the race, the nation.The Real Jesus of the Four Gospels | J. B. Atwater
The fundamental unit of the metric system is the meter (the unit of length).Soap-Making Manual | E. G. Thomssen
The solar day is the fundamental unit of time, not only in daily life but in astronomical practice.
It is not given to many men to know the ultimate essentials of all horror, concentrated into one fundamental unit.The Tree of Life | Catherine Lucille Moore
The metric system is the system of measurement of which the meter is the fundamental unit.The Style Book of The Detroit News | The Detroit News