What is the name of the bacterial shape that is rod-like?

The bacterial shape that is rod-like is called a bacillus. In this shape-based sense, “bacillus” is a general morphology term for an elongated, cylindrical bacterial cell.

Bacilli are one of the basic bacterial shapes commonly recognized under a microscope. Others include cocci, which are spherical, and spirilla or vibrios, which have curved or spiral forms. Rods can occur singly or in arrangements such as pairs called diplobacilli and chains called streptobacilli.

A frequent source of confusion is the difference between the shape term bacillus and the genus Bacillus. A bacterium can be rod-shaped without belonging to the Bacillus genus. For example, Escherichia coli and many Clostridium species are bacilli in shape, but they belong to different taxonomic groups.

Rod shape also does not determine Gram-stain result or lifestyle. Both Gram-positive and Gram-negative bacteria can be rod-shaped, and some rods are aerobic while others grow without oxygen.