pappusPronunciation: /ˈpapəs/Definition of pappus noun (plural pappi /-pʌɪ, -piː/) Botany the tuft of hairs on each seed of thistles, dandelions, and similar plants, which assists dispersal by the wind. Derivatives pappose adjective Origin: early 18th century: via Latin from Greek pappospappus in other Oxford dictionaries Definition of pappus in the US English dictionary