roux

UK: /ruː/ US: (ro̅o̅)

WordReference Random House Unabridged Dictionary of American English © 2025

roux (ro̅o̅), n. 

1. Food a cooked mixture of butter or other fat and flour used to thicken sauces, soups, etc.

• Latin russus red-brown, red-haired, akin to ruber red
• French (beurre) roux brown (butter)
• 1805–15

Collins Concise English Dictionary © HarperCollins Publishers::

roux / ruː/ noun (roux)

1. a mixture of equal amounts of fat and flour, heated, blended, and used as a basis for sauces

Etymology: 19th Century: from French: brownish, from Latin russus russet