'Solid' in the Bible

I gave you milk to drink, not solid food; for you were not yet able to receive it. Indeed, even now you are not yet able,

For though by this time you ought to be teachers, you have need again for someone to teach you the elementary principles of the oracles of God, and you have come to need milk and not solid food.

But solid food is for the mature, who because of practice have their senses trained to discern good and evil.