فَيْفَاءُ

is synonym with فَيْفٌ, q. v.: therefore its ا is augmentative, (S, M,) according to Sb (M) and Mbr: (S:) and it signifies (S, M, O,) also (M) a smooth [desert such as is termed] صَحْرَاء: (S, M, O:) its plural is فَيَافٍ. (S, M, O, K. [In the CK, this plural is written فِيافٌ, as though it were a plural of فَيْفٌ.])