By convention, when the word parasite is used without qualification, it often refers to

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The term "parasite" without qualification generally refers to protozoan or helminthic organisms that live on or within another organism (the host) and depend on the host for survival. Yeast and fungi can also be considered parasites, but they are typically referred to as "fungal parasites." Bacteria and Archaea can be parasitic, but they are more commonly referred to as "pathogens." Lichens are symbiotic organisms and are not considered parasites.

By Convention, When the Word Parasite Is Used Without Qualification