"shunning light" (in reference to bats, cockroaches, etc.), 1650s, from Latin lucifugus "light-shunning," from stem of lucere "to shine" (from suffixed (iterative) form of PIE root *leuk- "light, brightness") + stem of fugax "apt to flee, timid," figuratively "transitory, fleeting," from fugere "to flee" (see fugitive (adj.)).
