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Webster 1913 Edition

Noun.

The state or quality of being local; affection for a particular place.

A method of speaking or acting peculiar to a certain district; a local idiom or phrase.

localism ‎(countable and uncountable, plural localisms)

(countable, linguistics) a linguistic feature that is unique to a locality
(uncountable) Attachment to a particular local place; feelings or policies which emphasize local phenomena
- 2010, The Economist, Jul-Aug 2010, p. 27:
  Localism may strengthen not just the selfless (eg, people who want to build a village hall) but also the selfish (who want to stop any new building in their backyard).