Definition

Noun: A fundamental measure is one of a small set of independent, base quantities upon which all other measurements in a system are defined. These are the foundational units from which derived units are constructed.

Usage

This term is used in the context of metrology (the science of measurement) and physics to describe the core, irreducible units of a measurement system. The most common modern system is the International System of Units (SI), which has seven base quantities.

Examples

• The meter is a fundamental measure for length in the SI system.
• Time, as measured in seconds, is considered a fundamental measure.
• The development of a coherent measurement system begins by defining its fundamental measures.

Advanced Usage

• The choice of which quantities are considered fundamental measures can evolve with scientific understanding. For example, the ampere, the unit of electric current, is a fundamental measure in SI, but its definition is based on a fixed numerical value of the elementary charge.
• The phrase "fundamental measure" emphasizes the conceptual and definitional priority of these units over derived units like velocity (meters per second) or force (newtons).

Variants and Related Words

• Base unit: A more common and precise synonym for a fundamental measure within a specific system like SI.
• SI base unit: Refers specifically to one of the seven fundamental measures in the International System of Units (meter, kilogram, second, ampere, kelvin, mole, candela).
• Fundamental unit: A less formal synonym.

Synonyms

• Base quantity
• Base unit
• Fundamental unit

Related Concepts (Not Phrasal Verbs or Idioms)

• Derived unit: A unit of measurement that is defined as a combination of the fundamental measures (e.g., the newton for force is kg·m/s²).
• System of measurement: A complete set of units, including fundamental and derived measures, used in a consistent scheme (e.g., the metric system, imperial system).

Noun

1. one of the four quantities that are the basis of systems of measurement