unselfishness has 1 distinct synonym spread across 1 of its 2 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is selfishness.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
the quality of not putting yourself first but being willing to give your time or money or effort etc. for others
“rural people show more devotion and unselfishness than do their urban cousins”
Synonyms, antonyms and the broader and narrower relations for unselfishness come from Princeton University’s WordNet. Full sources and licences.