  We show that Majoron, the pseudo-Nambu-Goldstone boson resulting from the
spontaneous breaking of global lepton number symmetry, can present itself as a
viable freeze-in type of dark matter in a mass range keV-GeV, thanks to the
explicit higher dimensional Lepton number breaking operator. Interestingly, the
proposal is restricted within the simplest extension of the Standard Model with
two singlet right-handed neutrinos and a singlet scalar so to address light
neutrino mass and spontaneous breaking of lepton number symmetry respectively.
The desired amount of Majoron production takes place from the annihilations of
right-handed neutrinos indicating an intriguing connection between neutrino
physics and dark matter.
