/ ˌrevəˈluːʃn; NAmE / noun
1.
[ C , U ] an attempt, by a large number of people, to change the government of a country, especially by violent action :
a socialist revolution
the outbreak of the French Revolution in 1789
to start a revolution
a country on the brink of revolution
—see also counter-revolution , revolt
2.
[ C ] revolution (in sth) a great change in conditions, ways of working, beliefs, etc. that affects large numbers of people :
a cultural / social / scientific, etc. revolution
A revolution in information technology is taking place.
—see also Industrial Revolution
3.
[ C , U ] revolution (around / on sth) a complete circular movement around a point, especially of one planet around another :
the revolution of the earth around the sun
—see also revolve
4.
(also informal rev ) [ C ] a circular movement made by sth fixed to a central point, for example in a car engine :
rotating at 300 revolutions per minute
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WORD ORIGIN
late Middle English : from Old French , or from late Latin revolutio(n-) , from revolvere roll back, from re- back (also expressing intensive force) + volvere roll.