semiannual

from WordNet (r) 3.0 (2006)

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

from The Collaborative International Dictionary of English v.0.48

Semiannual \Sem`i*an"nu*al\, a.
   Half-yearly.
   [1913 Webster]

from Moby Thesaurus II by Grady Ward, 1.0

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