Etymology
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lour (v.)
"to frown," late 13c. variant of lower (v.2). Related: Loured; louring.
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lower (v.2)
"to look dark and menacing," also lour, from Middle English louren, luren "to frown, scowl" (early 13c.), "to lurk" (mid-15c.), from Old English *luran or from its cognates, Middle Low German luren, Middle Dutch loeren "lie in wait." The form perhaps has been assimilated to lower (v.1). Related: Lowered; lowering.
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