Webster's Revised Unabridged Dictionary · 1913

Rubaiyat

Rubaiyat , noun, plural

[Arabic rubā'iyāh quatrian, plural of rubā'iy having four radicals, from rubā' four.]

Quatrians; as, the Rubaiyat of Omar Khayyam. Sometimes in pl. construed as sing., a poem in such stanzas.