bac·te·ri·um
(bak-tîre-əm)
(bak-tîre-əm)n.pl. bac·te·ri·a(-tîre-ə)
1. Any of various prokaryotic microorganisms of the domain Bacteria that may be free-living, saprophytic, commensal, or pathogenic and that vary widely in terms of morphology, oxygen tolerance, nutritional and temperature requirements, and motility.Also called eubacterium.
2. Any of the prokaryotic organisms, such as an archaeon. Not in scientific use.
[New Latinbacterium, fromGreekbakterion, diminutive ofbaktron, rod; see bak- in the Appendix of Indo-European roots.]
bacteriumtop: rod-shaped bacterium
Pseudomonas aeruginosa
center:spherical-shaped bacterium
Staphylococcus aureus
bottom: spiral-shaped bacterium
Treponema pallidum
bacterium
bacterium