There`up·on' adverb 1. Upon that or this; thereon. 'They shall feed thereupon .' Zeph. ii. 7. 2. On account, or in consequence, of that; therefore. « [ He] hopes to find you forward, . . . And thereupon he sends you this good news.» Shak. ... Found on http://www.encyclo.co.uk/webster/T/41
adverb immediately after that; `thereupon the entire class applauded`; `with that, she left the room`; `I therewith withdraw my complaints` Found on https://www.encyclo.co.uk/local/20974