bacillus
ba•cil•lus (bəsil´əs) n. , pl. -cil´li´ (-ī´)
[[ModL < LL, little rod < L bacillum, dim. of baculus, var. of baculum, a stick < IE base *bak-, staff > peg, Gr baktron]]
1 any of a genus (Bacillus) of rod-shaped bacteria that occur in chains, produce spores, and are active only in the presence of oxygen
2 any rod-shaped bacterium: distinguished from coccus, spirillum
3 [usually pl.] loosely, any of the bacteria, esp. those causing disease
