bacteroid

Short definition from Wiktionary

Noun

1. 1
   A micro-organism such as a bacterium or yeast.
2. 2
   A bacterium of the species Bacteroides.
3. 3
   A symbiotic form of the nitrogen-fixing bacterium Rhizobia, or the root nodule that it produces.

Adjective

1. 1
   Resembling bacteria.