The word 'residuum' focuses on what remains after the most significant or larger portion is removed. The experiment's residuum could hold the key to our findings.
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Physical Remnants
Refers to the physical leftover of something, can be tangible like sediment or debris. Cleaning the ancient vase, we noticed a residuum of dust inside.
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Academic Usage
Mostly used in academic or formal texts, not common in everyday conversations. The residuum in the reactor was preserved for further analysis.