This expression attaches to nouns to indicate that even that noun is included or that the noun is the last thing remaining out of a group of included things.

It is usually used only in negative situations.

Details

This expression can be replaced with '까지' with almost no change in meaning.

그동안 서로 바빠서 만나지 못하다가 연락까지 끊기고 말았다.

그 나라는 오랫동안 진행된 내전으로 노인과 어린이들까지 전쟁에 동원되고 있는 실정이다.

However, while '마저' can only be used in negative statements '까지' can be used in both positive and negative statements.

미경 씨는 똑똑하고 마음씨도 곱고 얼굴마저 예쁘다. ✕

While the expressions 조차 and 마저 can both be used interchangeably in negative statements to indicate the addition of some fact or state of affairs to what has already been stated, note the following differences between them.

Kimchi Reader

Emphasizes that the additionally included listed item is least expected.

Details

Usage

Often to an extreme extent and/or leading to an undesirable outcome.

Emphasis

Adding 도 makes the meaning more emphatic.