  We generalize Kato's adiabatic theorem to nonunitary dynamics with an
isospectral generator. This enables us to unify two strong-coupling limits: one
driven by fast oscillations under a Hamiltonian, and the other driven by strong
damping under a Lindbladian. We discuss the case where both mechanisms are
present and provide nonperturbative error bounds. We also analyze the links
with the quantum Zeno effect and dynamics.
