attendance has 1 distinct synonym spread across 1 of its 3 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 nonattendance.
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 act of being present (at a meeting or event etc.)
the frequency with which a person is present
“a student's attendance is an important factor in her grade”
the number of people that are present
“attendance was up by 50 per cent”
Synonyms, antonyms and the broader and narrower relations for attendance come from Princeton University’s WordNet. Full sources and licences.