Vorticella \Vor`ti*cel"la\, n.; pl. E. Vorticellas, L. Vorticell[ae]. [NL., dim. fr. L. vortex. See Vortex.]

(Zo["o]l.) Any one of numerous species of ciliated Infusoria belonging to Vorticella and many other genera of the family Vorticellid[ae]. They have a more or less bell-shaped body with a circle of vibrating cilia around the oral disk. Most of the species have slender, contractile stems, either simple or branched.

Source: Webster's Revised Unabridged Dictionary (1913)