Definition of oidium in English:

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Pronunciation: /ōˈidēəm/

noun (plural oidia /ōˈidēə/)

1 Botany A type of fungal spore (conidium) formed by the breaking up of fungal hyphae into cells, especially as produced by powdery mildews.
2A fungal disease affecting vines, caused by a powdery mildew.
  • The fungus is Uncinula necator (formerly Oidium tuckeri), family Erysiphaceae, subdivision Ascomycotina.
Example sentences
  • The effects of phylloxera were first noted in France in 1863, just as the country was recovering from another great scourge of 19th century European viticulture: oidium, or powdery mildew, which was first noted in 1847.


Mid 19th century: modern Latin, from Greek ōion 'egg' + the diminutive suffix -idion.

For editors and proofreaders

Syllabification: o·id·i·um

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