Variant of Kassia/Kezia, from Hebrew meaning 'cassia tree,' a fragrant spice mentioned in the Bible.
Kasiyah is a variant of Kezia (also spelled Keziah, Cassia, or Kassia), a name of ancient Hebrew origin. In the Book of Job, Kezia (קְצִיעָה, Qetziah) is the second of Job's three daughters born after his restoration — sisters to Jemimah and Keren-Happuch — and her name refers to the cassia plant, a fragrant bark related to cinnamon that was prized across the ancient Near East for its use in sacred anointing oils. The Book of Exodus specifically lists cassia as one of the ingredients in the holy anointing oil of the Tabernacle, making Kezia's name both botanical and consecrated.
The name's most remarkable historical bearer may be Kassia (also Kassiane, c. 805–865 CE), a Byzantine abbess, poet, and composer who is one of the few women of the medieval world whose music has survived and is still performed today. Kassia studied at an imperial court in Constantinople, reportedly impressed Emperor Theophilos so greatly during the bride-show of 830 CE that he almost chose her as empress — until a sharp-tongued exchange led him to pick another.
She went on to found a convent and write some of the most sophisticated liturgical poetry of her era; her hymn for Holy Wednesday is still sung in Orthodox churches every year. In its Kasiyah form, the name arrives in the contemporary world wearing a new phonetic garment — softer, more flowing — while carrying all of this ancient freight. The fragrance of cassia, the stubbornness of Kassia the poet, the survival of Job's daughters after catastrophe: the name has always been given to girls expected to endure beautifully.