coccus

This term describes a specific morphological classification of bacteria characterized by a round or oval shape. It is used primarily in microbiology to categorize pathogens based on their physical structure and their reaction to Gram staining, which determines the composition of the cell wall. As a Latin-derived biological term, the plural form is irregular. While the English plural "cocci" is the standard scientific usage, the word functions as a countable noun in a clinical or laboratory setting, referring to individual bacterial cells or groups of such cells.