spi·ro·chete 
(spīrə-kēt′)
(spīrə-kēt′)n.
Any of various slender, spiral, motile bacteria of the order Spirochaetales, many of which are pathogenic, causing syphilis, relapsing fever, yaws, and other diseases.
[New Latin Spīrochaeta, genus name : Latin spīra, coil; see SPIRE2 + New Latin chaeta, bristle, hair; see CHAETA.]
spi′ro·chetal (-kētl) adj.