What is Lumbocostal?

Lumbocostal definition and meaning on Dictionary terms:
noun, plural luA.mens, [loo-muh-nuh] /E?lua??mE?a??nE?/.
Optics. the unit of luminous flux, equal to the luminous flux emitted in a unit solid angle by a point source of one candle intensity. Abbreviation: lm
Anatomy. the canal, duct, or cavity of a tubular organ.
Botany. (of a cell) the cavity that the cell walls enclose.