rudiment
— Noun
– English
~ the remains of a body part that was functional at an earlier stage of life; "Meckel's diverticulum is the rudiment of the embryonic yolk sac"
rudimentary
— Adjective
– English
~ being in the earliest stages of development; "rudimentary plans"
rudimentary
— Adjective
– English
~ being or involving basic facts or principles; "the fundamental laws of the universe"; "a fundamental incompatibility between them"; "these rudimentary truths"; "underlying principles"