Rubā'ī (English spelling) rubai

Japanese: rubā‘ī（英語表記）rubai

…But the 9th century was the infancy of Persian literature. In the 10th century, the Samanid dynasty, which ruled over Central Asia and eastern Iran with Bukhara as its capital, adopted a national cultural policy, revived the system of court poets that had been extinct since the fall of the Sassanid dynasty, and endeavored to protect and encourage Persian poets. As a result, the Persian Literary Revival occurred, and the foundations of Persian literature were established during this period. Rudaki, who was praised as the “flower of the Bukhara court,” was a great poet representing the 10th century. He wrote poetry using all the major forms of Persian poetry, including odes (qaṣida), epics (mathnavi), lyric poems (ghazals), and quatrains (rubā'ī), and was later revered as the “father of Persian poetry.” The main characteristic of this period was the rise of odes by court poets and national epics, both of which reflected the spirit of the times. …

From Rubaiyat

…Ruba'i is the plural form of the Persian quatrain, Rubā'ī, meaning collection of quatrains. Rubā'i is said to have originated from folk songs and is a uniquely Persian form of poetry.

*Some of the terminology explanations that mention "rubā'ī" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…しかし9世紀は揺籃期で，10世紀にブハラを都として中央アジアとイラン東部を支配したサーマーン朝が民族文化政策を採り，ササン朝滅亡以来絶えていた宮廷詩人制度を復活させ，ペルシア詩人の保護･奨励に努めた結果，〈ペルシア文芸復興〉が起こり，この時代にペルシア文学の基礎が確立された。〈ブハラ宮廷の華〉とうたわれたルーダキーは10世紀を代表する大詩人で，頌詩(カシーダqaṣīda)，叙事詩(マスナビーmathnavī)，抒情詩(ガザルghazal)，四行詩(ルバーイーrubā‘ī)などペルシア詩の主要な詩形をすべて用いて作詩し，後世〈ペルシア詩の祖〉と仰がれた。この時代の大きな特色は宮廷詩人による頌詩と民族叙事詩の勃興で，ともに時代精神の反映であった。…