In a symbiotic relationship, the smaller organism is called the symbiont, and the larger organism is called the host.

Here's a breakdown:

* Symbiont: The smaller organism in the relationship. It can be a bacteria, fungus, virus, or another organism.

* Host: The larger organism that provides a habitat or resources for the symbiont.

Keep in mind that the specific terms used to describe the types of symbiosis can be more precise:

* Parasitism: The symbiont benefits at the expense of the host (e.g., a tapeworm in a human intestine).

* Mutualism: Both the symbiont and the host benefit from the relationship (e.g., a bee pollinating a flower).

* Commensalism: The symbiont benefits, but the host is neither harmed nor helped (e.g., barnacles on a whale).