Definition:Spring/Equilibrium Position

Definition
The equilibrium position of a body $B$ attached to a spring $S$ is the position it occupies when $S$ is exerting no force upon $B$.

For an ideal spring obeying Hooke's Law $\mathbf F = -k \mathbf x$, the equilibrium position is set to be the point $\mathbf x = \bszero$.