  We argue that the axion arising in the solution of the strong CP problem can
be identified with the Majoron, the (pseudo-)Goldstone boson of spontaneously
broken lepton number symmetry. At low energies, the associated $U(1)_L$
becomes, via electroweak parity violation and neutrino mediation,
indistinguishable from an axial Peccei-Quinn symmetry in relation to the strong
interactions. The axionic couplings are then fully computable in terms of known
SM parameters and the Majorana mass scale, as we illustrate by computing the
effective couplings to photons and quarks at two loops.
