a small usually single-celled asexual reproductive body produced by many nonflowering plants and fungi and some bacteria and protozoans and that are capable of developing into a new individual without sexual fusion; "a sexual spore is formed after the fusion of gametes"
(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 plants