We consider a very weakly interacting KeV majoron as dark matter particle (DMP), which provides both the critical density ρcr=1.88×10−29h2 g/cm3 and the galactic scale Mgal ∼m3Pl/m2J∼1012M⊙(mJ/1KeV)−2 for galaxy formation. The majoron couples to leptons only through some new 'directly interacting particles', called DIPS, and this provides the required smallness of the coupling constants. If the masses of these DIPS are greater than the scale Vs characterizing the spontaneous violation of the global lepton symmetry they are absent at the corresponding phase transition (T∼Vs) and the majorons are produced during the phase transition, never being in thermal equilibrium during the history of the universe. In the alternative case mDIP<Vs the majorons can be for a short period in thermal equilibrium. This scenario is not forbidden by nucleosynthesis and gives a reasonable growth factor for the density fluctuations compatible with COBE. A possible signature is an X-ray line at Eγ=mJ2, produced by the decay J→γ+γ. A model is described which realizes the possibility of the KeV majoron as DMP and may also lead to observable rates for decays such as $\mu \ra e \gamma$ and $\mu \ra 3e$.