Definition
A global reference system that defines the size and shape of the Earth and provides a single, standardized coordinate framework for expressing latitude, longitude, and elevation anywhere in the world. WGS-84 is the reference datum used by GPS and by virtually all modern aeronautical charts and navigation databases.
Plain English
It is the agreed-upon mathematical model of the Earth that GPS and aviation charts use so that every position on the planet is measured from the same starting point. When two systems both use WGS-84, a given latitude and longitude refers to exactly the same spot on the ground.
Context Anchor
You may see World Geodetic System 1984 in GPS, charting, navigation database, and coordinate discussions.
Derivation
Geodetic comes from the Greek geodaisia, meaning 'division of the Earth' -- the science of measuring the Earth's shape and size. The '1984' marks the year this version of the global model was adopted; earlier versions existed (WGS-60, WGS-72) and were refined as measurement technology improved.
Why Pilots Care
Accurate use of this datum ensures GPS coordinates on the chart match the aircraft's displayed position, preventing navigation errors during cross-country flight or instrument approaches.
Analogy
Think of it like everyone agreeing to use the same ruler and the same starting point for the whole Earth. Once everyone uses that same reference, a latitude and longitude point means the same place to each user.
Grounding Statement
When your GPS shows a latitude and longitude, World Geodetic System 1984 is the Earth model that gives that position its exact meaning.
Intuition Check
Do not read “1984” as meaning the data is old or outdated. Here it names the reference system version used to define positions worldwide.
Example Sentence 1
All waypoints in the GPS navigation database are referenced to WGS-84, which matches the datum used on current FAA instrument approach charts.
Example Sentence 2
Before loading the flight plan the pilot confirmed the database was referenced to the World Geodetic System 1984.