Adjectives for describing shapes of bacteria
| Shape singular/plural | Description | Example | Plural | Adjective |
|---|---|---|---|---|
| Coccus/cocci | Spherical bacteria; can be in pairs (diplococci) or chains (streptococci) | Gonococcus Pneumococcus | Gonococci Pneumococci | Gonococcal Pneumococcal |
| Bacillus/bacilli* | Rod-shaped bacteria | Bacillary | ||
| Spiral | Spiral-shaped bacteria | Spirochaete† | Spirochaetes | Spirochaetal |
*Not to be confused with Bacillus the genus.
†Most common example for sexually transmitted pathogens, that is, Treponema pallidum. Alternative forms are vibrio and spirillum.