A limit which mandates that no white dwarf (a collapsed, degenerate star) can be more massive than about 1.4 solar masses. Any degenerate object more massive must inevitably collapse into a neutron star.
The Chandrasekhar limit is the maximum mass of a stable white dwarf star. It was named after Subrahmanyan Chandrasekhar, the Indian-American astrophysicist who predicted it in 1930. White dwarfs, unlike main sequence stars, resist gravitational collapse primarily through electron degeneracy pressure, rather than thermal pressure. The Chandrasekhar limit is the mass above which electron degeneracy pressure in the star's core is insufficient to balance the star's own gravitational self-attraction. Consequently, white dwarfs with masses greater than the limit undergo further gravitational collapse, evolving into a different type of stellar remnant, such as a neutron star or black hole. Those with masses under the limit remain stable as white dwarfs.The currently accepted value of the limit is about 2.864 × 1030 kg.
Source: wikipedia, NASA