  A convincing explanation of the smallness of neutrino masses is represented
by the Type-I Seesaw mechanism, where the two measured neutrino mass
differences can be generated by introducing at least two right-handed
neutrinos. In an ultraviolet complete model, it is possible to dynamically
generate the heavy Majorana scale through the spontaneous symmetry breaking of
a global Abelian symmetry and the most economical realisation consists in
coupling the two exotic neutral leptons to a singlet complex scalar field. The
associated Goldstone boson is often dubbed as Majoron, which may achieve a
non-vanishing mass by means of a small term that explicitly breaks the Abelian
symmetry. In a generic model, the neutrino and Majoron mass generation
mechanisms are completely uncorrelated. In this paper, instead, we reduce the
landscape of possible models proposing a unique, minimal and predictive
framework in which these two types of masses are strictly tied and arise from
the same source. Bounds from various terrestrial and astrophysical experiments
are discussed.
