Which type of bacteria is referred to as bacilli?

Bacilli refer specifically to rod-shaped bacteria. The term "bacillus" is derived from the Latin word for "little staff" or "rod," accurately describing their elongated and cylindrical shape. This classification is a key characteristic in microbiology, allowing for easier identification and categorization of bacteria during analysis.

In contrast, the spherical-shaped bacteria are referred to as cocci, cubic-shaped bacteria do not have a specific classification in the context of standard bacterial morphology, and oval-shaped bacteria can exist but are not typically categorized under the common bacterial shapes. Therefore, rod-shaped is the precise and widely accepted definition for bacilli in microbiological studies.