Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
upper-class is an adjective meaning "occupying the highest socioeconomic position in a society". It carries one recorded sense.
occupying the highest socioeconomic position in a society
Definitions, synonyms and semantic relations for upper-class come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.