roux

As a noun roux

is a mixture of fat (usually butter) and flour used to thicken sauces and stews.

As an adjective doux is

(of champagne) sweet.

As nouns the difference between roup and roux

is that roup is an outcry or roup can be an infectious disease of poultry caused by trichomonas gallinae while roux is a mixture of fat (usually butter) and flour used to thicken sauces and stews.

As a verb roup

is to cry or shout.

As nouns the difference between roun and roux

is that roun is (obsolete) a secret or mystery while roux is a mixture of fat (usually butter) and flour used to thicken sauces and stews.

As a verb roun

is (obsolete) to whisper.