Involving or including more than one political party. It is mostly used about how a country's politics is built: a multiparty system, multiparty elections, multiparty talks. The point of the word is usually a contrast with one-party rule — when reporters say a country has held its first multiparty elections, they are saying that for the first time, voters had a real choice and other parties were allowed to stand. So the word often carries an unspoken 'and that is progress'. It is a formal, news-and-politics word; in ordinary talk people just say 'the other parties' or name them. There is a second, quieter use outside politics, in law and technology, where party means 'a side in an agreement': a multiparty contract, a multiparty video call. That sense simply means more than two sides are involved, with no political flavour at all — the software world uses it this way constantly. Students meet the political sense far more often in reading and exams. Note the spelling: normally written solid in modern writing, though older texts hyphenate it as multi-party, and both are accepted.