Englishfor English speakers
boundary
Noun
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A boundary is the line around something's outside edge.
The elephants have to live within the boundary of the park or risk being shot.
There have been many times in their lives when the boundaries between their personal and professional lives have disappeared.
More manufactured goods are crossing international boundaries every day.
An international commission that regulates the boundary waters between the U.S. and Canada.
index
Noun
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An index is an alphabetical (A to Z) list, usually at the back of a book, where you can find the pages in a book that talk about particular things or words.
Look in the index to see where they talk about Chomsky.
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An index shows the level of prices, wages, etc. so you can compare them with those of an earlier date.
On Wall Street, the Dow Jones index closed 10 points up at 2,731.23.
index
Verb
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If you index something, you make an index (guide) for it.
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If you index something to a certain price level, you make it go up or down with that level.