Term: gnat: any of various small biting flies: midges; biting midges; black flies; sand flies
Broader: dipterous insect: insects having usually a single pair of functional wings (anterior pair) with the posterior pair reduced to small knobbed structures and mouth parts adapted for sucking or lapping or piercing | Unrelated: alga: primitive chlorophyll-containing mainly aquatic eukaryotic organisms lacking true stems and roots and leaves