the.com/law of inertia

means A body at rest stays at rest, and a body in motion keeps moving at the same speed and direction, unless an outside force acts on it.

from Rooted in the Latin 'iners' — 'without skill or activity,' from 'in-' (not) plus 'ars' (skill, art) — originally describing idleness or laziness in people. Galileo's early experiments with rolling balls challenged the ancient Aristotelian belief that motion needed constant force to continue, and Newton later formalized the idea as his First Law of Motion, borrowing 'inertia' to name matter's stubborn tendency to keep doing whatever it was already doing.