Triptych
Triptych , noun
[Greek {not transcribed} consisting of three layers or plates; {not transcribed} (see Tri-) + {not transcribed}, {not transcribed}, a fold, layer.]
Anything in three parts or leaves.
(a)
A writing tablet in three parts, two of which fold over on the middle part.
(b)
A picture or altarpiece in three compartments.