'Rudiments' in the Bible

So we also, when we were children, were held in bondage under the rudiments of the world:

but now that ye have come to know God, or rather to be known by God, how turn ye back again to the weak and beggarly rudiments, whereunto ye desire to be in bondage over again?

Beware lest any man spoil you through philosophy and vain deceit, after the tradition of men, after the rudiments of the world, and not after Christ.

Wherefore if ye be dead with Christ from the rudiments of the world, why, as though living in the world, are ye subject to ordinances,

For when by reason of the time ye ought to be teachers, ye have need again that some one teach you the rudiments of the first principles of the oracles of God; and are become such as have need of milk, and not of solid food.