biannual

from WordNet (r) 3.0 (2006)

biannual
    adj 1: occurring or payable twice each year [syn: {semiannual},
           {biannual}, {biyearly}, {half-yearly}]

from The Collaborative International Dictionary of English v.0.48

Biannual \Bi*an"nu*al\, a. [Pref. bi- + annual.]
   Occurring twice a year; half-yearly; semiannual.
   [Webster 1913 Suppl.]

from Moby Thesaurus II by Grady Ward, 1.0

29 Moby Thesaurus words for "biannual":
      annual, biennial, bimonthly, biweekly, catamenial, centenary,
      centennial, daily, decennial, diurnal, fortnightly, hebdomadal,
      hourly, menstrual, momentary, momently, monthly, quarterly,
      quotidian, secular, semestral, semiannual, semimonthly, semiweekly,
      semiyearly, tertian, triennial, weekly, yearly

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