-spo·ri·um \ˈspōrēəm, -pȯr-\noun combining form Etymology: New Latin, from spora spore + -ium 1.plural-spo·ria\-ēə\also-sporiums: (such) a coat or layer of a spore wall < endosporium > 2.: plant having (such) a spore — in generic names < Helminthosporium >