first lady

Short definition from Wiktionary

Noun

1. 1
   The leading woman in a specified field of endeavor.
2. 2
   Alternative letter-case form of First Lady.
3. 3
   The wife of the chief executive of a nation; especially the wife of the President of a country; or a woman (e.g. a relative) who takes on similar public duties, as when the chief executive is unmarried.
4. 4
   The wife of a pastor.
5. 5
   Alternative letter-case form of first lady.