Luciferous: light giving.
Lucifugous: fleeing the light: applied to nocturnal forms or those that live in concealment.
Lumen: the cavity of an organ: the inner surface of a tube: the hollow portion of a gland or vesicular structure.
Luminescence: applied to the light of fire-flies, as a substitute for phosphorescence.
Lumper: one who, in describing species or genera recognizes only prominent or obvious characters to the exclusion of minor color or variable characters of maculation or structure: see splitter.
Lunaris or Lunate: crescent-shaped: formed like a new moon.
Lunula: a small lunule or crescent.
Lunulae: in Hymenoptera, crescent-shaped marks near the orbits.
Lunulate: a line, when made up of a series of small lunules.
Lunule: a lunate mark or crescent.