nanoplanktonEnglishOxford New American Dictionarynanoplankton /ˌnanōˈplaNGktən, ˌnænoʊˈplæŋktən / ▸ noun Biology very small unicellular plankton, at the limits of resolution of light microscopy. – ORIGIN early 20th century : from German, from Greek nanos ‘dwarf’ + plankton.