[ ɪ'kweɪʒ(ə)n ]
■ noun
1》 the process of equating one thing with another.
2》 Mathematics a statement that the values of two mathematical expressions are equal (indicated by the sign =).
3》 Chemistry a symbolic representation of the changes which occur in a chemical reaction, expressed in terms of the formulae of the molecules or other species involved.
Phrases
~ of the first (or second etc.) order Mathematics an ~ involving only the first derivative, second derivative, etc.
~ of state Chemistry an ~ showing the relationship between the values of the pressure, volume, and temperature of a quantity of a particular substance.
~ of time the difference between mean solar time (as shown by clocks) and apparent time (indicated by sundials), which varies with the time of year.
Origin
ME: from L. aequatio(n-) , from aequare (see equate ).