All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu 'alyhi wa sallam, is His slave and Messenger.
It is forbidden for any woman to modify, shave or remove the hair of her eyebrows whether by using a thread or razor or any other means. Removing the facial hair is prohibited in Islam and the Prophet Muhammad, sallallaahu ‘alayhi wa sallam cursed those who indulge in such practices. Imaams Al-Bukhari and Muslim narrated that ‘Abdullaah Ibn Mas’ood said, "Allaah curses those women who practice tattooing and those who get themselves tattooed, those women who remove their eyebrow hair or remove the eyebrow hair of others, and those who make artificial spaces in between their teeth – thereby changing the creation of Allaah.”
This saying of his reached a woman from the tribe of Bani Asad who then came (to him) and said, "I have come to know that you have cursed such-and-such (women)?" He replied, "Why should I not curse these whom Allaah's Apostle has cursed and who are (cursed) in Allaah's Book!" The woman (Umm Ya’qoob said), "But I have read the whole Quran and I did not find in it what you say." He said, "If you had really read it, you would have found it. Did you not read: {And whatsoever the Apostle gives you take it and whatsoever he forbids you, you abstain (from it).}[Quran: 59.7]” She replied, "Yes, I did," He said, “Indeed, Allaah’s Apostle, sallallaahu ‘alayhi wa sallam, forbade such things.” She said, “But I see your own wife doing such things.” He said, “Go and see.” So the woman went, but found nothing to support her claim, and so she returned and said, “I did not see anything.” Upon that, ‘Abdullaah said, “If my wife was as (you had claimed), then I would not have associated with her.”
Allaah Knows best.