In field theory, a nonlocal Lagrangian is a Lagrangian, a type of functional L [ ϕ ϕ ( x ) ] containing terms that are nonlocal in the fields ϕ ϕ ( x ) , i.e. not polynomials or functions of the fields or their derivatives evaluated at a single point in the space of dynamical parameters (e.g. space-time). Examples of such nonlocal Lagrangians might be: