Technically in writing, 'Deadwood' refers to unnecessary words, phrases or any expanded verbiage. As we say well-chosen words add the meaning and power to your essay, however deadwood or clutter, or some editors call wasted word, gets in the way. 

Deadwood 很显然是由两个词dead和wood组成，死亡的木头，直接就可翻译成自然界的枯木枝或朽木来用。不过在写作范畴内，朽木还可表达另一个意思，即指代文章中不必要和多余的字眼或废话。要是教授说某段话是 Deadwood的话，就类似于 “老太太的裹脚布又臭又长” 那种批评了。

How to recognise deadwood?

' For example, rather than simply writing because, since, or if, some students feel compelled to clutter their sentences with empty phrases. Here are some common ones: by virtue of the fact that, due to the fact that, for the simple reason that, inasmuch as, in light of fact that... ' (- Bridges to better writing)

一篇论文里哪些是朽木呢？在《Bridges to better writing》这本书里指出很多学生故意拖长文章篇幅的现象，比如明明可以用 becasue, since 这些简明扼要的词语表示“因为”，却偏偏用什么 by viture of the fact that... 这些超长词组。回想自己刚开始学写论文的日子，可不是嘛，有字数要求又写不出来的话，就到处塞字眼儿，现在看来都是些没啥实际用处的Deadwood，一堆朽木哈哈。