The upper parts of shoes above the sole; or slang for stimulant drugs like amphetamines.
From 'upper,' the adjective meaning higher or top part, plus the plural suffix '-s.' As slang for drugs, it emerged in the mid-20th century among musicians and drug users.
Shoes are such complex items that 'uppers' became a technical term in shoe-making—but the slang meaning as stimulant drugs is much darker, showing how the same word can mean something innocent in one context and very serious in another.
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