pertaining to rudiments or first principles; elementary

a rudimentary knowledge of geometry.

of the nature of a rudiment; undeveloped or vestigial.

primitive.

adjective

additional , advanced , derivative , developed , extra , nonessential

adjective

abecedarian , basal , beginning , early , elemental , elementary , embryonic , immature , initial , introductory , larval , nuts-and-bolts , primary , primitive , simple , simplest , uncompleted , undeveloped , vestigial , basic , rudimental , abecedary , abortive , contingent , fragmental , fundamental , germinal , inchoate , inchoative , incipient , incomplete , nascent , potential