Brachyptery is an anatomical condition meaning that an animal has very reduced, non-functional wings. Such as animal may be described by the adjective "brachypterous".
A brachypterous wings are very common in the insect world when the insect give up the ability to fly hence reduce it's fly muscles so save energy. This condition is known in parasitic insect that lives on other animals, insect in isolated oceanic islands without natural enemies or even females that use the extra benefit energy to manufacture more eggs. Sometimes brachypterous insects can exist with fully developed wings (macropterous) individuals or wings development depends on the temperature so in cold winter wings are reduced and in summer they are full develop for immigration.