pepper-and-salt
US /ˌpep.ər.ənˈsɔːlt/
UK /ˌpep.ər.ənˈsɔːlt/

1.
a fabric woven with dark and light threads to produce a mottled gray effect
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He wore a suit made of pepper-and-salt tweed.
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The old blanket had a classic pepper-and-salt pattern.
1.
having a mottled gray appearance, typically referring to hair that is streaked with gray or white
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His hair was a distinguished pepper-and-salt.
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The old man's beard was a mix of black and white, a true pepper-and-salt.