any of various unsegmented marine worms of the phylum Echiura, comprising the spoonworms.
Origin: < NL Echiurida, var. of Echiura < Gk échi(s) viper + -oura neut. pl. of -ouros -tailed (deriv. of ourá tail); Cf. Echiurus a genus of the phylum; see -ida
[ek-ee-yoo
r-id] 