DuckCorp Dico

Found one definition

1.                 From English - German Ding/FreeDict dictionary ver. 1.9-fd1:
                   
   
   
                   
                     
   aestival /ˈiːstɪvəl/
   sommerlich <adj>, Sommer…, in den Sommermonaten <adj> [biol.]  [envir.]
            Note: nachgestellt
      Synonyms: estival, characteristic of summer