What is the meaning of Protist?

Any of the eukaryotic unicellular organisms—including protozoans, slime molds and some algae—historically grouped into the kingdom Protista (or Protoctista), now distributed over several clades.

Any single-celled eukaryote, prokaryote or sponge .

Any single-celled eukaryote or prokaryote .

Any single-celled eukaryote .

protist (unicellular organism)

protist

Source: wiktionary.org