say it: duh-MAYN
demesne is a noun meaning "extensive landed property (especially in the country) retained by the owner for his own use". It carries 2 recorded senses.
extensive landed property (especially in the country) retained by the owner for his own use
“the family owned a large estate on Long Island”
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 demesne come from Princeton University’s WordNet. The pronunciation comes from the CMU Pronouncing Dictionary. Commonness is measured against a corpus of everyday English. Full sources and licences.