much less, not only
This expression is used to indicate that not only is the content in the preceding clause not easily realized but also that the content in the following clause is even more so.
Thus, the content of the following clause is usually more basic or simpler than that of the preceding clause.
Usually, this expression takes the form of -기는커녕 도(조차) 안 -/못 -/없다.
This expression is also used when the speaker wants to express the fact that the content of the preceding clause is naturally difficult to realize or achieve and when the content of the following clause represents a different, or even the opposite, situation of what is expected in the preceding clause.
In this case, the expression is often used together with 오히려.
1. When used with nouns, this expression takes the form of 은커녕/는커녕.
2. With almost no change in meaning, -기는커녕 can be replaced with -는 것은 고사하고 while 은커녕/는커녕 can be replaced with 은/는 고사하고.
Used typically in negative sentences in the form 'A는커녕 B', meaning that not only did a negative event A happen (or a positive event A did not happen), but that an even more negative event B happened (or a less positive event B did not happen either).