Spirillum \Spi*ril"lum\, n. [NL., dim. of L. spira a coil.]
1. (Biol.) A genus of common gram-negative motile
microorganisms (family {Spirillaceae}) having the form of
spiral-shaped filaments. They are obligately
microaerophilic, and do not ferment carbohydrates.
--Stedman.
[1913 Webster]
2. A species of bacteria ({Borrelia recurrentis}, also known
as {Obermeier's spirillum}), once believed to belong to
the genus {Spirillum}, which causes relapsing fever.
[PJC]