what is pneumococcus
Definition of pneumococcus. plural. pneumococci. play \-ËkÃ¤k-ËsÄ«, -ËsÄ; -ËkÃ¤-ËkÄ«, -ËkÄ\. : a bacterium (Streptococcus pneumoniae) that causes an acute pneumonia involving one or more lobes of the lung.