Lovely 17+ Diplococcus. The bacterium diplococcus pneumoniae was first described less than a century ago. Grapelike clusters of cells, staphylococci; Information and translations of diplococcus in the most comprehensive dictionary definitions resource on the web. Circa 1881, in the meaning defined above. Diplococcus - Diplococcus Wikipedia The bacterium diplococcus pneumoniae was first described less than a century ago. Information and translations of diplococcus in the most comprehensive dictionary definitions resource on the web.