rudiment

A fundamental element, principle, or skill, as of a field of learning.

Something in an incipient or undeveloped form.

An imperfectly or incompletely developed organ or part.

To furnish with first principles or rules; ground; settle in first principles.

Anything which is in an undeveloped state; the principle which lies at the beginning or bottom of any development; an unformed or unfinished beginning.

An element or first principle of any art or science; especially, in the plural, the beginning, first steps, or introduction to any branch of knowledge; the elements or elementary notions.

In biology: That which is rudimentary; that which is in its first or an early stage of development, which may or may not be continued; the beginning or foundation of any part or organ: as, the rudiment of the embryo which is to go on to maturity; the rudiment of an organ whose further development has been arrested or aborted

That which is vestigial; a vestigial or aborted part, organ, or structure; an abortion; a vestige.

To furnish with first principles or rules; to insrtuct in the rudiments.