rudimentary in WordNet English dictionary

1. being or involving basic facts or principles
   "the fundamental laws of the universe"; "a fundamental incomatibility between them"; "these rudimentary truths"; "underlying principles"
   fundamental  rudimentary  underlying 
   
2. being in the earliest stages of development
   "rudimentary plans"
   rudimentary 
   
3. not fully developed in mature animals
   "rudimentary wings"
   vestigial  rudimentary