abstruse adj. [ub-STROOSS]
深奥的
Definition
: difficult to comprehend: recondite
：难以理解的，难以掌握的：深奥的
注：recondite：深奥的，难解的，隐藏的
Did You Know？
Look closely at the following Latin verbs, all of which are derived from the verb trudere ("to push, thrust"): extrudere, intrudere, obtrudere, protrudere. Remove the last two letters of each of these and you get an English descendant whose meaning involves pushing or thrushing. Another trudere offspring, abstrudere, meaning "to push away" or "to conceal," gave English abstrude, meaning "to thrust away," but that 17th-century borrowing has fallen out of use. An abstrudere descendant that has survived is abstruse, an adjective that recalls the meaning of its Latin parent abstrūsus, meaning "concealed."
词源/词根演化：abs-（off, away from）+ trudere ("to push, thrust") --> abstrude (v. "to thrust away") --> abstruse (adj. "hidden, concealed, secret")
仔细看看下面几个拉丁动词：extrudere, intrudere, obtrudere, protudere，他们都来自于动词trudere（推，挤）。把这些动词的最后两个字母拿掉，我们就得到了相应的英语词汇：extrude，intrude，obtrude，protrude，这些词也都与“推，挤”有关系。另外一个trudere的拉丁派生词，abstrudere，意思是“推开”或“隐藏”，为英语世界带来了动词abstrude，意思是“推开”，不过这个17世纪的借词现在早已不再使用。不过abstrudere的后代abstruse却存活了下来，这个形容词让我们回忆起它的拉丁祖先abstrūsus，意思是“隐藏的”。
Example
- "Today's phsics breakthroughs tend to be so abstruse that summarizing them is like trying to explain the financial-derivatives market to a three-year-old."
--- The National Review, 16 Apr. 2018
现代物理学的突破成果越来越深奥难懂了，将其概述的难度有点类似于向一个3岁小孩解释金融衍生品市场。
注：financial-derivativs：金融衍生品 - "Before the Apple Macintosh, the first computer to popularize point-and-click, people using home computers had to familiarize themselves with abstruse text commands."
--- Clive Thompson, The New York Times, 18 Nov. 2018
苹果的麦金塔电脑让点击操作流行起来，在此之前，家用电脑的用户不得不去熟悉那些复杂难懂的文本命令行。
注：popularize：普及，使...流行；familiarize：使...熟悉（注意例句中的用法：主语人 + familiarize themselves with sth.）；text commands：指在电脑的终端窗口中输入的命令行，例如LINUX的ls, cd命令。