say it: sahy-muhl-TAY-nee-uhs
simultaneous is an adjective meaning "occurring or operating at the same time". It carries one recorded sense.
occurring or operating at the same time
“a series of coincident events”
Definitions, synonyms and semantic relations for simultaneous come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.