[¦lō ¦mas ¦eks‚rā ′bī‚ner·ē] (astronomy) A binary system consisting of a low-mass (typically less than 1 solar mass), late-type star and a neutron star or black hole that accretes material through Roche-lobe overflow, resulting in the emission of relatively soft x-rays. Abbreviated LMXRB.SeeLMXRBSeeLMXRB