Definition of yessum in English:

yessum

Pronunciation /ˈyesəm/ /ˈjɛsəm/

exclamation

dialect, dated US
  • Used as a polite form of assent addressed to a woman.

    ‘“You feel all right?” she asked. “Yessum.”’
    • ‘I won't talk about Bagger Vance… (yessum, weeza all trying ta’ fuget about Bagga Vance ‘roun these here parts!)’
    • ‘That is the first time I have heard the phrase yessum mister since Little House on the Prairie all those years ago.’
    • ‘Yessum, Miss Daisy, I'll drive you to the store, yessum.’

Origin

Early 20th century representing a regional pronunciation of yes ma'am.