Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
decentalisation is a noun meaning "the social process in which population and industry moves from urban centers to outlying districts". It carries one recorded sense.
the social process in which population and industry moves from urban centers to outlying districts
Forms marked · are formed by the regular rule rather than recorded in the source data. English keeps a few hundred irregulars and the rest follow the pattern, so the rule is right far more often than not — but it is a rule, and the mark says so.
Definitions, synonyms and semantic relations for decentalisation come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.