Plate tectonics

Etymology

From Greek "tektonikos" (of building), from "tekton" (builder, carpenter) — the same root as “architect.” The full theory came together in the 1960s, vindicating Alfred Wegener’s earlier, ridiculed idea of continental drift.

noun phrase · /PLAYT tek-TON-iks/
The theory that Earth’s outer shell is broken into huge plates that slowly drift, colliding and pulling apart to build mountains, oceans, and earthquakes.
What it names
The single mechanism behind seemingly unrelated facts — matching coastlines across oceans, earthquake belts, volcanic chains, and the slow rearrangement of the continents.
Example
Plate tectonics explains why the Himalayas are still rising: the Indian plate is grinding into Asia and buckling the crust upward.
Related idea
Plate tectonics is the deep engine that raises land; erosion is the surface force that wears it back down. Mountains exist in the tension between the two — built faster than they are ground away.