hol·o·plank·ton \ˌhälōˈplaŋktən, ˌhōl-\noun Etymology: International Scientific Vocabulary hol- + plankton : plankton composed of organisms that pass their whole life floating, drifting, or swimming weakly in the water — compare hemiplankton • hol·o·plank·ton·ic\| ̷ ̷ ̷ ̷(ˌ)plaŋk|tänik\adjective