plural noun1. parts or sections
the upper reaches of the Amazon
This year water levels in the middle and lower reaches of the Yangtze are unusuallyhigh.
2. parts or areas
the outer reaches of the solar system
Communications with the outer reaches of the empire were slow.
the farthest reaches of Cambodia
3. levels
the lower reaches of the organization
the higher reaches of the legal profession
the elites who dominated the higher reaches of the administration