多种相关的细长软体小动物，特别是环虫类、毛颚类、线虫类和扁形虫类；也包括许多昆虫的幼虫。

• any of numerous relatively small elongated soft-bodied animals especially of the phyla Annelida and Chaetognatha and Nematoda and Nemertea and Platyhelminthes; also many insect larvae.