NectocalyxNec`to*ca"lyx\, n.; pl. Nectocalyces. [NL., fr. gr. ? swimming + ? a calyx.] (Zo["o]l.) (a) The swimming bell or umbrella of a jellyfish of medusa. (b) One of the zooids of certain Siphonophora, having somewhat the form, and the essential structure, of the bell of a jellyfish, and acting as a swimming organ.