malacostraca Meaning, Definition & Usage

  1. noun largest subclass of Crustacea including most of the well-known marine, freshwater, and terrestrial crustaceans: crabs; lobsters; shrimps; sow bugs; beach flies
    subclass Malacostraca.

WordNet

Mal`a*cos"tra*ca noun plural
Etymology
NL., from Gr. soft + shell of a testacean.
Definitions
  1. (Zoöl.) A subclass of Crustacea, including Arthrostraca and Thoracostraca, or all those higher than the Entomostraca.

Webster 1913