a large, plump, pillow-shaped fruiting body of certain myxomycetes, formed by the aggregation of plasmodia into a single functional mass.
Origin: < Neo-Latin, originally a genus of Myxomycetes containing such a body < Greek aíthal(os) or aithál(ē) thick smoke, soot (akin to aíthein to kindle, burn) + Neo-Latin -ium-ium; so named from the smokelike spores