nanoplanktonEnglishOxford Dictionary of Englishnanoplankton /ˈnanə(ʊ)ˌplaŋ(k)tən / ▸ noun [mass 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.