Whatever you call them, you must treat them the same way as any other human being in Islam

Serve Allah, and join not any partners with Him; and do good to parents, kinsfolk, orphans, those in need, neighbours who are near, neighbours who are strangers, the companion by your side, the wayfarer (ye meet), and what your right hands possess(MMA) For Allah loveth not the arrogant, the vainglorious;-

And let those who cannot find a match keep chaste till Allah give them independence by His grace. And such of your slaves as seek a writing (of emancipation), write it for them if ye are aware of aught of good in them, and bestow upon them of the wealth of Allah which He hath bestowed upon you. Force not your slave-girls to whoredom that ye may seek enjoyment of the life of the world, if they would preserve their chastity. And if one force them, then (unto them), after their compulsion, lo! Allah will be Forgiving, Merciful.