Word Study
biannual
CIDE DICTIONARY
biannual, a. [Pref. bi- + annual.].
Occurring twice a year; half-yearly; semiannual. [Webster 1913 Suppl.]
OXFORD DICTIONARY
biannual, adj. occurring, appearing, etc., twice a year (cf. BIENNIAL).
Derivative
biannually adv.
THESAURUS
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, yearlyFor further exploring for "biannual" in Webster Dictionary Online