资料来源 : pyDict

一年二次的

资料来源 : Webster's Revised Unabridged Dictionary (1913)

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

资料来源 : WordNet®

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