Filaria and Roundworm

Filaria noun - Slender threadlike roundworms living in the blood and tissues of vertebrates; transmitted as larvae by biting insects.

Roundworm and filaria are semantically related. In some cases you can use "Roundworm" instead a noun "Filaria".

Roundworm noun - Unsegmented worms with elongated rounded body pointed at both ends; mostly free-living but some are parasitic.

Filaria and roundworm are semantically related. Sometimes you can replace term "Filaria" with "Roundworm", this nouns are similar.