rudimentary
adj
1 existing in an imperfect or undeveloped form 未充分发展的; 发育不成熟的; 退化的
Some breeds of dog have only rudimentary tails. 有些品种的狗尾巴只有退化的部分.
2 (derog 贬) elementary; (not more than) basic 初步的; (充其量)基本的
I have only a rudimentary grasp of physics. 我对物理学仅有初步的了解.