Spirillum \Spi*ril"lum\, n. [NL., dim. of L. spira a coil.]

(Biol.) A genus of common motile micro["o]rganisms (Spirobacteria) having the form of spiral-shaped filaments. One species is said to be the cause of relapsing fever.

Source: Webster's Revised Unabridged Dictionary (1913)