Noun
Roche lobe (plural Roche lobes)
(astronomy) The teardrop-shaped region around a star in a binary system within which orbiting material is gravitationally bound to that star.
In fact, the size of the equatorial ridge is comparable with the expected Roche lobe of the moon. Source: Internet
In this case, the stars are so close together that the larger giant is overflowing its Roche lobe and transferring material to the secondary, forming a semidetached system. Source: Internet
The other component is an intermediate mass star. citation Hercules X-1 is composed of a neutron star accreting matter from a normal star (HZ Herculis) probably due to Roche lobe overflow. Source: Internet
Semidetached binary stars are binary stars where one of the components fills the binary star's Roche lobe and the other does not. Source: Internet