"Rubaiyat of Omar Khayyam" is the title that Edward FitzGerald gave to his translation of a selection of poems, originally written in Persian and numbering about a thousand, attributed to Omar Khayyam (1048–1131), a Persian poet, mathematician and astronomer. A 'ruba'i' is a two-line stanza with two parts per line, hence the word rubáiyát (derived from the Arabic language root for "four"), meaning "quatrains".  As a work of English literature FitzGerald's version is a high point of the 19th century and has been greatly influential. Indeed, the term "Rubaiyat" by itself has come to be used to describe the quatrain rhyme scheme that FitzGerald used in his translations: AABA.
(Excerpt from Wikipedia)