What is the definition of equilibrium?

No, they can not be said to be in equilibrium. In mechanics language, "equilibrium" = "static equilibrium", meaning equilibrium at rest or on a constant velocity translation, excluding rotation or movement along a curved path (all w.r.t. an intertial frame).

The complement "dynamic equilibrium", meaning that inertia forces oppose accelerations, is unnecessary as it is impossible to not be in dynamic equilibrium. Therefore, the distinction is unnecessary and "static" is in general omitted.