Definition of unicellular in US English:



  • 1(of protozoans, certain algae, spores, etc.) consisting of a single cell.

    • ‘An interesting variant of normal photosynthesis is the simultaneous photoevolution of molecular hydrogen and oxygen by certain unicellular algae and in vitro cell-free preparations.’
    • ‘Although the evolution of well-mixed, unicellular microorganisms has been studied extensively, the evolution of filamentous microorganisms has not.’
    • ‘As compared to metazoans, the development of these unicellular organisms is likely less affected by dissociated heterochrony, which is considered a common phenomenon in metazoans.’
    • ‘However, the evolutionary distance between unicellular organisms and higher plants might be a serious setback when trying to obtain high expression, at the right time and cellular localization, of foreign genes in plants.’
    • ‘In the heliocentric perspective, our dear earth is a mere speck in this expanding infinite space where a very tenacious life came into existence in its oceans about two and half billion years ago in a unicellular body - the Amoeba.’
    1. 1.1 (of an evolutionary or developmental stage) characterized by the formation or presence of a single cell or cells.
      • ‘Second, the existence of unicellular life for one or two billion years without the formation of multicellular life wouldn't be a problem on Mars because it obviously was not a problem on Earth.’
      • ‘All further cell divisions from this unicellular stage of the human being occur by simple mitosis.’