-nəˌdē noun plural
Usage: capitalized
Etymology: New Latin, from Hydrachna, type genus (from hydr- + Greek achna, achnē foam, chaff) + -idae — more at ear
in some classifications : a large family of water mites (group Hydrachnellae) that includes all the common free-living mites of fresh water and a few parasites of the gills of mollusks and that is now usually broken up into numerous separate families