Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
cassius is a noun meaning "prime mover in the conspiracy against Julius Caesar (died in 42 BC)". It carries one recorded sense.
prime mover in the conspiracy against Julius Caesar (died in 42 BC)
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for cassius come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.