plec·trid·i·um \plekˈtridēəm\noun (pluralplectrid·ia \-ēə\) Etymology: New Latin, from Latin plectrum + New Latin -idium : a hammer-shaped or drumstick-shaped cell; especially: any of various rod-shaped bacteria formerly classed as a genus Plectridium in which one end becomes enlarged by the production of an endospore