The Collaborative International Dictionary
Nectostem
Nectostem \Nec"to*stem\, n. [Gr. nhkto`s swimming + E. stem.] (Zo["o]l.) That portion of the axis which bears the nectocalyces in the Siphonophora.
Wiktionary
nectostem
n. (context zoology English) That portion of the axis which bears the nectocalyx in siphonophores.