Protoctista Syllabification: (Pro·toc·tis·ta)Pronunciation: /ˌprōtäkˈtistə/ BiologyDefinition of Protoctista a kingdom or large grouping that is either synonymous with the Protista or equivalent to the Protista together with their multicellular descendants. Derivatives protoctistPronunciation: /ˈprōtäkˌtist/ noun Origin:modern Latin (plural), based on Greek prōtos 'first'Protoctista in other Oxford dictionaries Definition of Protoctista in the British & World English dictionary