What is the meaning of the word "al-Qaynāt" mentioned in the Hadith of the Messenger of Allah, peace and blessings be upon him: "When al-Qaynāt and musical instruments appear?"

The hadith of Imran ibn Husayn, narrated by al-Tirmidhi and authenticated by al-Albani, indicates that sinking into the earth (khasf), transformation (maskh), and being pelted with stones (qadhf) will occur in the Muslim nation if female singers and musical instruments become prevalent and alcoholic beverages are consumed. The term "qaynāt" in the hadith refers to enslaved singing women.