Apterous: without wings.
Apterygogenea: those insects that are wingless in all stages and presumed to be descended from ancestors which never were winged: see pterygogenea.
Apterygota: = apterygogenea; see pterygote.
Aquamarine -us: sea green: pale green with predominant blue and a little gray [nile green].
Aquatic: living wholly in water.
Aquatilia: cryptocerous Hemiptera of truly aquatic habit.
Arachnoideous: resembling or similar to a cobweb.
Araneiform: spider-like in appearance.
Arboreal: living in, on, or among trees.
Arborescent: branching like the twigs of a tree.