Definition of millionheiress in English:

millionheiress

noun

rare, humorous
  • An heiress to a million pounds (dollars, etc.) or more.

Origin

Late 19th century; earliest use found in The Century Illustrated Monthly Magazine. From million + heiress, punningly after millionairess.

Pronunciation

millionheiress

/ˌmɪljəˈnɛːrɛs//ˌmɪljəˈnɛːrɪs/