Source : Webster's Revised Unabridged Dictionary (1913)

Aerenchym \A"["e]r*en`chym\, Aerenchyma \A`["e]r*en"chy*ma\, n.
   [NL. a["e]renchyma. See {A["e]ro-}; {Enchyma}.] (Bot.)
   A secondary respiratory tissue or modified periderm, found in
   many aquatic plants and distinguished by the large
   intercellular spaces.