名詞 rudiment:

1. the elementary stages of any subject (usually plural)
   同義詞：first rudiment, first principle, alphabet, ABC, ABC's, ABCs
2. the remains of a body part that was functional at an earlier stage of life

1. I have mastered the rudiments of economics.
   我已精通經濟學的基本原理。

ru.di.ment

n.（名詞）
Often rudiments A fundamental element, principle, or skill, as of a field of learning.
常作 rudiments 基本原理：某一學術領域的基本元素、原理或技巧
Often rudiments Something in an incipient or undeveloped form:
常作 rudiments 初級階段：處于早期或未發(fā)展階段的某物：
例句：
the rudiments of social behavior in children; the rudiments of a plan of action.
孩子社會活動的入門；一個行動計劃的雛形

Biology An imperfectly or incompletely developed organ or part.
【生物學】 未成熟的器官或部分：發(fā)育不完善或不完全的器官或部分

來源：
Latin rudomentum
拉丁語 rudomentum
from rudis [rough, unformed]
源自 rudis [粗糙的，未成形的]

【引伸】
ru.dimen.tal