'Lumina' definitions:

Definition of 'Lumina'

From: GCIDE

Lumen \Lu"men\, n.; pl. L. Lumina, E. Lumens. [L., light, an opening for light.]
1. (Photom.) (a) A unit of illumination, being the amount of illumination of a unit area of spherical surface, due to a light of unit intensity placed at the center of the sphere. (b) A unit of light flux, being the flux through one square meter of surface the illumination of which is uniform and of unit brightness. [Webster 1913 Suppl.]
2. (Biol.) An opening, space, or cavity, esp. a tubular cavity; a vacuole. [Webster 1913 Suppl.]