A Protist

1. (microbiology) Any of the eukaryotic unicellular organisms including protozoans, slime molds and some algae; historically grouped into the kingdom Protoctista.
   1. single-celled eukaryotes, prokaryotes and sponges [to 1959]
   2. single-celled eukaryotes and prokaryotes [1959–1969]
   3. single-celled eukaryotes [since 1969]