Escape Velocity
Etymology
An astronomy and rocketry term combining "escape" — from Old French "eschaper," ultimately Vulgar Latin "excappare," literally "to slip out of one's cloak" — with "velocity," from Latin "velocitas" ("swiftness"), from "velox" ("swift"). It names the exact speed at which kinetic energy overcomes a body's gravity.
noun phrase · /es-KAYP vuh-LOSS-ih-tee/
The minimum speed an object needs to break free of a gravitational pull for good, without further thrust.
What it names
A vivid metaphor for the threshold of effort past which something becomes self-sustaining — a startup, a career, a recovery — and below which it falls back.
Example
The band spent years playing empty bars before one song hit escape velocity and pulled everything else into orbit.
Related idea
Compare momentum, which is what you have once you are moving; escape velocity is the specific speed you must reach before momentum alone can carry you clear.