Englishfor English speakers
sludge
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noun
the precipitate produced by sewage treatment
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noun
any thick, viscous matter
bulk
Noun
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The bulk of something is the largest part of it.
The bulk of the shipment was headed for Toronto.
The great bulk of crime has always involved stealing of one kind or another.
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Someone or something's bulk is its size or amount, especially if it is large.
She took a deep breath, and, enormously grateful for the solid bulk of Leo at her back, she stepped inside.
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If you sell something in bulk, it is not individually packaged.
I usually buy nuts at the bulk food store.
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If you buy something in bulk, you buy large amounts.
The store offers discounts for buying in bulk.
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A bulk is an item that is moved about like cargo.
bulk
Verb
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If something bulks, it appears to be big in size.
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If you bulk something, you increase its' size; you expand it.
concentration
Noun
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A concentration is a large amount of something in one place or group.
The oil-sands in Alberta, Canada, contain high concentrations of oil.
The growing concentration of people in cities is causing new problems.
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Concentration is the ability to focus your attention on something.
Runners mustn't worry or do anything else to break their concentration.
A clean desk in a quiet place will help students improve concentration.
The government's concentration should be on helping those in the greatest need.
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The amount of solute in a solution; the concentration of a solution is measured in parts per million (ppm)