The property of a body to stay at rest or keep moving at constant velocity is called:

1. Newton's first law describes a tendency rather than a force. 2. The property of a body to remain at rest or to remain in motion with constant velocity is called inertia. 3. Mass is the quantitative measure of that property. 4. Momentum instead combines mass with a particular velocity. _Source: OpenStax College Physics for AP(R) Courses 2e (CC BY 4.0), Ch 4 'Dynamics: Force and Newton's Laws of Motion', sections 4.1-4.8_