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We’ve got loads of key subject terms in our subject glossaries. There are three ways of finding what you are looking for:

  • First click on the letters of the alphabet to browse for terms.
  • Select a subject from the drop-down menu above to filter the terms by Subject.
  • Or lastly, type the term you are looking for into the search box.


Here are some examples of the kinds of definitions you’ll find on this page.

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a number which combined with its inverse results in the identity 1, e.g. 4 × ¼ = 1.


a graph in which you replace the x-values with the y-values and the y...


a function that produces the size of an angle, given one of the angle's trigonometric ratios: If...

if one variable increases, the other variable decreases at a fixed rate.