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

Bifold \Bi"fold\, a. [Pref. bi- + fold.]
   Twofold; double; of two kinds, degrees, etc. --Shak.

资料来源 : WordNet®

bifold
     adj : capable of being folded into two parts, as with doors that
           are hinged together