Bacteroid (thing)

1. Resembles a bacterium.
2. A particular group of small, gram-negative, anaerobic, rod-shaped bacteria.
3. A cell which was modified from a bacteria that has become an endosymbiont within other organisms, like plants or marine animals.

From the BioTech Dictionary at http://biotech.icmb.utexas.edu/. For further information see the BioTech homenode.