Units and metrology terminology: In measurement systems, the term “fundamental units” is also commonly referred to by which name?

Introduction / Context:
Understanding unit systems is crucial for accurate scientific and engineering work. The International System of Units (SI) defines several “fundamental” quantities—such as length, mass, time, electric current—whose units form the basis for all derived units. Knowing that “fundamental units” are synonymous with “base units” ensures consistent terminology across disciplines and standards.

Given Data / Assumptions:

• The discussion concerns SI-style unit systems and their structure.
• “Fundamental units” means the set of units that are not derived from other units within the system.
• Examples include meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), mole (mol), and candela (cd).

Concept / Approach:

Base (fundamental) units are defined independently and serve as building blocks. Derived units (such as newton, volt, and ohm) are algebraic combinations of base units according to physical laws (for example, 1 N = 1 kg*m/s^2). Recognizing the distinction prevents dimensional-analysis mistakes and clarifies how measurement traces back to primary standards.

Step-by-Step Solution:

Verification / Alternative check:

Consulting metrology references and standards documents shows “base unit” as the formal SI term, with “fundamental unit” used informally as a synonym in many textbooks and lab manuals.

Why Other Options Are Wrong:

• atoms: A physical concept, not a unit classification.
• the metric system: A broad family of systems; base units are specific elements within SI.
• letter symbols: Merely abbreviations, not the classification.
• primitive units: Not a standard metrological term.

Common Pitfalls:

• Confusing “SI units” (all units) with “SI base units” (the fundamental subset).
• Assuming derived units are “less official.” They are standardized but constructed from base units.

Final Answer:

base units