Streptococcus pyogenes

Etymology
Streptococcus pyogenes:

streptos: "chain" (from greek στρεπτός, meaning "twisted", but used medically to refer to "chains")

coccos: "berry" (from greek κόκκος, meaning "berry")

pyo: "pus" (from greek πύος, meaning "pus")

genes: "to make" (from greek root -γεν, taken from greek γεννάειν, meaning "to beget")

Explanation
The bacteria Streptococcus pyogenes looks like a chain (streptos) of small round berry-like cells (coccos), and is responsible for a number of infections which produce (genes) pus (pyo).

Synonyms
GAS, or Group A Streptococcus (because it is of the genus Streptococcus and it presents the streptococcal group A antigen on its cell wall).

GABHS, or Group A Beta Hemolytic Streptococcus (since it causes beta-hemolysis, or breakage (lysis) of red blood cells (hemo-) in vitro)