Bacteroid and Bacteria

Bacteroid noun - A rodlike bacterium (especially any of the rod-shaped or branched bacteria in the root nodules of nitrogen-fixing plants).

Bacteria and bacteroid are semantically related. In some cases you can use "Bacteria" instead a noun "Bacteroid".

Bacteria noun - (microbiology) single-celled or noncellular spherical or spiral or rod-shaped organisms lacking chlorophyll that reproduce by fission; important as pathogens and for biochemical properties; taxonomy is difficult; often considered to be plants.

Bacteroid and bacteria are semantically related. Sometimes you can replace term "Bacteroid" with "Bacteria", this nouns are similar.