  We propose a new interpretation of Peccei-Quinn symmetry within the Standard
Model, identifying it with the axial $B + L$ symmetry i.e. $U(1)_{PQ} \equiv
U(1)_{\gamma_5(B+L)}$. This new interpretation retains all the attractive
features of Peccei-Quinn solution to strong CP problem but in addition also
leads to several other new and interesting consequences. Owing to the
identification $U(1)_{PQ} \equiv U(1)_{\gamma_5(B+L)}$ the axion also behaves
like Majoron inducing small seesaw masses for neutrinos after spontaneous
symmetry breaking. Another novel feature of this identification is the
phenomenon of spontaneous (and also chiral) proton decay with its decay rate
associated with the axion decay constant. Low energy processes which can be
used to test this interpretation are pointed out.
