'Child' in the Bible

This is why I have sent Timothy to you. He is my dearly loved and faithful son in the Lord. He will remind you about my ways in Christ Jesus, just as I teach everywhere in every church.

When I was a child, I spake as a child, I understood as a child, I thought as a child: but when I became a man, I put away childish things.

Brothers, do not become children in [your] understanding, but with respect to wickedness be as a child, and in [your] understanding be mature.

and last of all, as to the child untimely born, he appeared to me also.