Wiktionary
kharja
n. (label en poetry) The final (l/en: refrain) of a (l/en: muwashshah).
Wikipedia
Kharja
A kharja or kharjah ( tr. kharjah , meaning "final"; ; ; also known as markaz, is the final refrain of a muwashshah, a lyric genre of Al-Andalus (the Islamic Iberian Peninsula) written in Arabic or Ibero-Romance.
The muwashshah consists of five stanzas (bait) of four to six lines, alternating with five or six refrains (qufl); each refrain has the same rhyme and metre, whereas each stanza has only the same metre. The kharja appears often to have been composed independently of the muwashshah in which it is found.