Definition of thereunto in English:

thereunto

adverb

archaic, formal
  • To that.

    ‘his agent thereunto lawfully authorized in writing or by will’
    • ‘Henceforth, when I refer to ‘Olympic’ fencing I mean fencing using the electrical scoring apparatus and all the organizational and stylistic artifacts appertaining thereunto.’
    • ‘The undersigned, being thereunto duly authorized by their respective governments, have agreed upon the following articles, establishing and regulating the exchange of correspondence between the United States of America and the Hawaiian Kingdom.’

Pronunciation

thereunto

/ðɛːrˈʌntʊ/