Kalmar "moneron" ba kalmar da aka saba amfani da ita ba ce a cikin Ingilishi na zamani, kuma ba a samo ta a mafi yawan ƙamus na Turanci ba. zuwa hasashe, daɗaɗɗe, kwayoyin halitta unicellular wanda ake tunanin shine mafi sauƙi nau'in rayuwa. Ernst Haeckel, masanin ilmin halitta kuma masanin falsafa Bajamushe ne ya gabatar da wannan ra'ayi a cikin karni na 19.A yau, wannan kalma ba a yin amfani da ita sosai a ilmin halitta, saboda an maye gurbinsa da wasu ƙayyadaddun kalmomi masu dacewa don bayyanawa. iri-iri na kwayoyin halitta unicellular, kamar kwayoyin cuta, archaea, da protists.