[ae]stival

AEstival \[AE]s"ti*val\, a. [L. aestivalis, aestivus, fr. aestas
   summer.]
   Of or belonging to the summer; as, [ae]stival diseases.
   [Spelt also {estival}.]
   [1913 Webster]
    

86 Moby Thesaurus words for "aestival":
      arctic, autumn, autumnal, beryl-green, berylline, blood-hot,
      blood-warm, blue-green, bluish-green, boreal, brumal, calid,
      canicular, chartreuse, chloranemic, chlorine, chlorotic, citrine,
      citrinous, emerald, equatorial, equinoctial, foliaged, genial,
      glaucescent, glaucous, glaucous-green, grassy, green,
      green as grass, green-blue, greenish, greenish-blue,
      greenish-yellow, greensick, hibernal, hiemal, holly, ivy,
      ivy-green, leafy, leaved, luke, lukewarm, midsummer, midwinter,
      mild, olivaceous, olive, olive-green, out of season, porraceous,
      room-temperature, seasonal, smaragdine, solstitial, spring,
      springlike, subtropical, summer, summerlike, summerly, summery,
      sunny, sunshiny, temperate, tepid, thermal, thermic, toasty,
      tropical, unfrozen, verdant, verdurous, vernal, vernant, vert,
      virescent, warm, warm as toast, warmish, winter, winterlike,
      wintery, wintry, yellowish-green