lose track has no recorded synonym. 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 keep track.
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.
fail to keep informed or aware
“She has so many books, she just lost track and cannot find this volume”
Synonyms, antonyms and the broader and narrower relations for lose track come from Princeton University’s WordNet. Full sources and licences.