alumina

American  

[uh-loo-muh-nuh] / əˈlu mə nə /

noun

1. the natural or synthetic oxide of aluminum, Al 2 O 3 , occurring in nature in a pure crystal form as corundum.

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alumina British  

/ əˈluːmɪnə /

noun

1. another name for aluminium oxide

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alumina Scientific  

/ ə-lo̅o̅′mə-nə /

1. Any of several forms of aluminum oxide used in aluminum production and in abrasives, refractories, ceramics, and electrical insulation. Alumina occurs naturally as the mineral corundum and, with minor traces of chromium and cobalt, as the minerals ruby and sapphire, respectively. In its hydrated form it also occurs as the rock bauxite. Also called aluminum oxide. Chemical formula: Al ₂ O ₃ .

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Etymology

Origin of alumina

1780–90; < Latin alūmin-, stem of alūmen alum ¹ + -a ⁴

Compare meaning

How does alumina compare to similar and commonly confused words? Explore the most common comparisons:

• alumina vs. aluminum

Example Sentences

When overseas aluminum smelters shut down, it can hurt Alcoa’s business, because it reduces demand for raw alumina.

From Barron's • Mar. 30, 2026

Morgan analyst William Peterson wrote in a recent note to clients that roughly a third of Alcoa’s alumina capacity is contracted to “key players” in the Middle East, including EGA and Alba.

From MarketWatch • Mar. 30, 2026

It mines bauxite, the raw material for aluminum, refines it into alumina powder, and operates smelters that turn alumina to finished aluminum.

From Barron's • Mar. 30, 2026

“Most aluminum smelters only hold a few weeks’ supply of alumina, which could further tighten availability,” they add.

From The Wall Street Journal • Mar. 19, 2026

A mineral of the feldspar family, triclinic in crystallization, and in composition a silicate of alumina and soda.

From Webster's Unabridged Dictionary by Webster, Noah