'Child' in the Bible

Now I say that so long as an heir is a child, he in no respect differs from a slave, although he is the owner of everything,

But we see that the child of the slave-girl was born in the common course of nature; but the child of the free woman in fulfilment of the promise.

For it is written, "Rejoice, thou barren woman that bearest not, break forth into a joyful cry, thou that dost not travail with child. For the desolate woman has many children--more indeed than she who has the husband."

Yet just as, at that time, the child born in the common course of nature persecuted the one whose birth was due to the power of the Spirit, so it is now.