Main Entry:

oid·i·um

Pronunciation:

\ō-ˈi-dē-əm\

Function:

noun

Inflected Form(s):

plural -ia \-dē-ə\

Etymology:

New Latin, from o- + -idium

Date:

1857

1 a: any of a genus (Oidium of the family Moniliaceae) of imperfect fungi many of which are now considered to be conidial stages of various powdery mildews b: one of the small conidia borne in chains by various fungi (as an oidium) —called also arthrospore2: a powdery mildew especially of grapes caused by an oidium