Opposed to egoism in a fundamental or complete way; characterized by selflessness and concern for others.
From antiegoistic + -al (alternate adjective-forming suffix). The -al version emphasizes a more thorough or systematic opposition to egoistic principles.
The doubled suffix in 'antiegoistical' (both -ic and -al) shows how important this concept was—writers wanted multiple ways to express deep opposition to selfishness.
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