• (n.) One of a tribe of beetles (Malacodermata), with a soft and flexible body, as the fireflies.
Mal'a·co·derm noun [ Greek ... soft + ... skin.] (Zoology) One of a tribe of beetles ( Malacodermata ), with a soft and flexible body, as the fireflies. 
malacoderm, malacodermatous 1. Having a soft skin. 2. A soft-skinned animal; an animal of any of the various groups called Malacodermata.